On Monday, December 22, 2014 10:36:41 AM UTC-5, Danny D. wrote:
Stormin Mormon wrote, on Mon, 22 Dec 2014 07:54:59 -0500:

If you're safe with a VOM, here's the technique:

I'm perfectly fine with 120/220V and can easily work with my
Fluke 75 on the furnace. I just need to know what to check,
bearing in mind that it's not at first obvious where the power
comes in yet.



I've never seen a furnace where it's not obvious where the power
comes in. I'm beginning to agree with Stormin.




You can get into the small box, and check for polarity and
if the ground is connected.

I can't imagine that the power polarity has reversed, on its own,
but, as you note, I should check it (since the flashing is hard
to understand and one interpretation of the flashes might be that
the power polarity is reversed).

Of course, that only matters for DC, right?

No, you can reverse the hot and neutral on AC. But as I said
before, it's virtually impossible for that to have happened and
I doubt anything to do with the power to the furnace is the problem.


So I'd need to know *where* the DC is coming from, since the line
voltage is AC (yes, I know a neutral isn't the same as a hot, nor
even the same as a ground, but, in terms of polarity, switching
a neutral with a hot shouldn't matter for AC motors or step-down
transformers (which I presume exist near the circuit board).

I hesitate to suggest people open up safety boxes and work
with live power, some folks can't do that safely. Prefer not
to go into a lot of detail on an open forum.

I have no problem whatsoever working around power.

On 12/22/2014 11:12 AM, Danny D. wrote:
My Fluke 75 is a good meter, which I've had for something
like 30 years. So, *using* a meter isn't at all a problem.

The problem is knowing what measurements to take.

To that end, this control board summary is a start:
https://c4.staticflickr.com/8/7511/1...a7b9a83c_h.jpg

As is this wiring control schematic:
https://c1.staticflickr.com/9/8616/1...d2721b93_h.jpg

And, of course, as is the overall furnace circuit schematic:
https://c4.staticflickr.com/8/7560/1...e91c4626_b.jpg

All of which I'm new to, but, which I will print and pore over
to see what basic control and power inputs to test with my
trusty DMM.


Black is hot, white is neutral, and green is
ground. You test at the little box I mentioned
earlier.

If it's the 31 code, I suspect you've got a bad
limit switch, not enough air flow, and the limit
switch finally gave out. I've seen two of those,
this year so far.

-
..
Christopher A. Young
Learn about Jesus
www.lds.org
..

On 12/22/2014 11:16 AM, Danny D. wrote:
trader_4 wrote, on Mon, 22 Dec 2014 06:51:01 -0800:

Besides, I'd bet 99% that nothing is wrong with the power.

I'll check that the white (neutral) has no voltage difference
with green or bare (ground), and that the black (hot) has
line voltage (120VAC) to both the neutral and ground, but, like
you, I am 99.9% sure that can't possibly be the problem.

The problem is "probably" described in this flow chart though...
https://c4.staticflickr.com/8/7506/1...6bb628a5_c.jpg


With that clogged air filter, I'd be thinking
bad thermal limit switch. I replaced one this
year in my own furnace, and one about a week
later for a customer.


-
..
Christopher A. Young
Learn about Jesus
www.lds.org
..

trader_4 wrote, on Mon, 22 Dec 2014 08:21:13 -0800:

I've never seen a furnace where it's not obvious where the power comes
in. I'm beginning to agree with Stormin.

OK. Fair enough. I haven't looked hard enough mainly because
I really don't think the problem is a reversed polarity on the
AC circuit.

First off, the thing is AC, so, "most" AC items don't care
whether the hot or neutral are reversed anyway; but more
importantly, nothing was done to reverse the hot and neutral.

Looking at my pictures, clearly the line voltage comes in right
at the middle, from the overhanging flexible metal BX cable:
https://c4.staticflickr.com/8/7516/1...72dc89861a.jpg

So, I'll pop off the cover of the box on the inside of that
connection - but - really - that will just tell me what I already
know must be the case - which is that the AC "line voltage" isn't
reversed.

But, I'll check it - and report back - with pictures.

On 12/22/2014 11:21 AM, trader_4 wrote:
bearing in mind that it's not at first obvious where the power
comes in yet.



I've never seen a furnace where it's not obvious where the power
comes in. I'm beginning to agree with Stormin.


CY: Hello! BX cable on top, to small box.
Earth to Danny!


Of course, that only matters for DC, right?

No, you can reverse the hot and neutral on AC. But as I said
before, it's virtually impossible for that to have happened and
I doubt anything to do with the power to the furnace is the problem.


CY: I've seen reversed polarity, and also open
grounds.

I hesitate to suggest people open up safety boxes and work
with live power, some folks can't do that safely. Prefer not
to go into a lot of detail on an open forum.

I have no problem whatsoever working around power.

CY: Well, in that case, the job is completed,
and you can post about it.

-
..
Christopher A. Young
Learn about Jesus
www.lds.org
..

trader_4 wrote, on Mon, 22 Dec 2014 08:21:13 -0800:

No, you can reverse the hot and neutral on AC. But as I said before,
it's virtually impossible for that to have happened and I doubt anything
to do with the power to the furnace is the problem.

I agree that hot and neutral *can* be reversed, but, from a practical
standpoint, other than the safety of two-wire grounded items, it
makes no difference.

So, when they're talking polarity reversal in the continuous-blink
scenario, I wonder if they're talking about the DC voltage, where
polarity can make a huge difference.

I doubt either one was reversed, simply because nothing was touched,
but, methinks they may be talking DC and not AC anyway.

Nonetheless, I'll pop that box off in the middle of the furnace
and measure the voltages (yes, I know what all the colors mean,
including white, black, red, if it's there, and green or bare).

I didn't check if it's 220V, but that just means there will be
two hots and a neutral, instead of a hot and a neutral.

On Monday, December 22, 2014 11:34:27 AM UTC-5, Danny D. wrote:
trader_4 wrote, on Mon, 22 Dec 2014 08:21:13 -0800:

No, you can reverse the hot and neutral on AC. But as I said before,
it's virtually impossible for that to have happened and I doubt anything
to do with the power to the furnace is the problem.

I agree that hot and neutral *can* be reversed, but, from a practical
standpoint, other than the safety of two-wire grounded items, it
makes no difference.

So, when they're talking polarity reversal in the continuous-blink
scenario, I wonder if they're talking about the DC voltage, where
polarity can make a huge difference.


No, they are talking about polarity reversed at the incoming AC,
ie hot and neutral. How would you ever get DC reversed on the circuit
board?

On Monday, December 22, 2014 11:24:39 AM UTC-5, Stormin Mormon wrote:
On 12/22/2014 11:12 AM, Danny D. wrote:
My Fluke 75 is a good meter, which I've had for something
like 30 years. So, *using* a meter isn't at all a problem.

The problem is knowing what measurements to take.

To that end, this control board summary is a start:
https://c4.staticflickr.com/8/7511/1...a7b9a83c_h.jpg

As is this wiring control schematic:
https://c1.staticflickr.com/9/8616/1...d2721b93_h.jpg

And, of course, as is the overall furnace circuit schematic:
https://c4.staticflickr.com/8/7560/1...e91c4626_b.jpg

All of which I'm new to, but, which I will print and pore over
to see what basic control and power inputs to test with my
trusty DMM.


Black is hot, white is neutral, and green is
ground. You test at the little box I mentioned
earlier.

If it's the 31 code, I suspect you've got a bad
limit switch, not enough air flow, and the limit
switch finally gave out. I've seen two of those,
this year so far.


It's nothing to do with airflow. He says he gets the flashing
from the LEDs indicating a fault as soon as power is applied,
before there is even a call for heat.

On 12/22/2014 11:29 AM, Danny D. wrote:
Looking at my pictures, clearly the line voltage comes in right
at the middle, from the overhanging flexible metal BX cable:
https://c4.staticflickr.com/8/7516/1...72dc89861a.jpg

So, I'll pop off the cover of the box on the inside of that
connection - but - really - that will just tell me what I already
know must be the case - which is that the AC "line voltage" isn't
reversed.

But, I'll check it - and report back - with pictures.


We'd expect nothing less from the professional
you are.

-
..
Christopher A. Young
Learn about Jesus
www.lds.org
..

On 12/22/2014 11:39 AM, trader_4 wrote:
On Monday, December 22, 2014 11:24:39 AM UTC-5, Stormin Mormon wrote:
If it's the 31 code, I suspect you've got a bad
limit switch, not enough air flow, and the limit
switch finally gave out. I've seen two of those,
this year so far.


It's nothing to do with airflow. He says he gets the flashing
from the LEDs indicating a fault as soon as power is applied,
before there is even a call for heat.


On my own furnace, I did get a fault code when
it powered up, and turned out to be a bad limit.

So my personal experience is.....


-
..
Christopher A. Young
Learn about Jesus
www.lds.org
..

Stormin Mormon wrote, on Mon, 22 Dec 2014 12:49:48 -0500:

But, I'll check it - and report back - with pictures.
We'd expect nothing less from the professional you are.

I gathered the testing equipment:
https://c4.staticflickr.com/8/7541/1...ea2b8a1c_b.jpg

I turned off the wall switch (it's turned on in this pic):
https://c4.staticflickr.com/8/7498/1...481232cf_b.jpg

I removed the cover of the inlex box from the BX cable:
https://c4.staticflickr.com/8/7511/1...594e782c_b.jpg

I separated the hot (black), neutral (white) & ground (green):
https://c4.staticflickr.com/8/7573/1...1a9fd07a_b.jpg

Turning power on, I tested neutral to ground at 0 volts AC:
https://c4.staticflickr.com/8/7533/1...a061993a_b.jpg

Turning power on, I tested hot to ground at nominally 120VAC.
https://c1.staticflickr.com/9/8638/1...8709828b_b.jpg

Turning power on, I tested hot to neutral at nominally 120VAC.
https://c4.staticflickr.com/8/7490/1...7fb5ddc8_b.jpg

I turned the power off, and reconnected the wires as before.

If the power is reversed, it's not at the inlet BX cable
connection to the unit.

What I mostly want to find is the big red button that says
"reset", but I don't see it. I see a bunch of smaller limit
resets, all of which I've pressed already.

Stormin Mormon wrote, on Mon, 22 Dec 2014 11:31:41 -0500:

CY: I've seen reversed polarity, and also open grounds.

The grounds seem good, tested from green to the metal case.
https://c1.staticflickr.com/9/8561/1...45432dbc_c.jpg

I agree that hot and neutral *can* be reversed, but, from a practical
standpoint, other than the safety of two-wire grounded items, it
makes no difference.


I suggest you read my previous post that explains how the flame sensor circuit works.

You can lead a horse to water......

Mark

trader_4 wrote, on Mon, 22 Dec 2014 08:37:51 -0800:

No, they are talking about polarity reversed at the incoming AC,
ie hot and neutral. How would you ever get DC reversed on the circuit
board?

The incoming power, at least at the BX cable coming into the furnace,
is not reversed, but, clearly "something" is wrong, so I do
appreciate the advice as to what to look for.

A few things I did in the meantime, which "may" have changed the
situation is that I opened up all the vents in the house, most
of which had been closed for some reason (almost certainly since
last winter), which means the vent airflow was certainly stifled.

I opened all the suckers:
https://c4.staticflickr.com/8/7563/1...ca4af62b_b.jpg

And all the blowers:
https://c4.staticflickr.com/8/7478/1...a422228b_b.jpg

And, I ascertained that there is no V-shaped filter in the top
(left) side of the furnace itself:
https://c4.staticflickr.com/8/7491/1...8312f3fe_c.jpg

This lack of v-shaped filters is apparently normal, as it is
described on the furnace cover sticker, which says:
"Horizontal furnace: Filters are located external of furnace.
Consult installer for location."
https://c4.staticflickr.com/8/7474/1...0f645731_c.jpg

Interestingly, since most of the vents were closed, I might assume
the furnace had shut off due to lack of air, but I can't find
what the sticker also says is the "RESET" button:
"Auxiliary limit control may be located on blower housing or
top of furnace. To RESET, push button on control firmly.
Refer to USERS MANUAL for more information. Call qualified
serviceman if failure continues."

Also, the sticker talks about a "fusible link", which I also
haven't found yet:
https://c1.staticflickr.com/9/8575/1...a6bf6b65_c.jpg
"This furnace is equipped with a fusible element or manual reset
limit switch in burnder compartment and/or draft diverter to
protect against overheat conditions that can result from
inadequate combustion air supply or blocked vent conditions."

Just in case, I hit all the reset buttons I could find, starting
with the two manual limit switches:
https://c4.staticflickr.com/8/7496/1...acc7329a_c.jpg

When I press the brown button on the manual limit switch, nothing
happens (I had expected a spring-loaded type of interaction):
https://c4.staticflickr.com/8/7490/1...550d1ee2_c.jpg

I pressed the brown button on the blocked vent tube switch:
https://c4.staticflickr.com/8/7580/1...19b8f191_c.jpg

There were no buttons on the flame sensor and hot surface igniter,
so, I merely wiggled the wires to ensure they were on snugly:
https://c1.staticflickr.com/9/8651/1...7fe7ca9f_c.jpg

I suspect this is the backside of the fusible link, which likewise,
I wiggled the wires to ensure they were on tightly:
https://c4.staticflickr.com/8/7498/1...4fb55b63_b.jpg

I also flipped the on-off switch, on the gas valve itself, a few times:
https://c1.staticflickr.com/9/8681/1...d011aced_c.jpg

I also wiggled all the wires and connections on the control board:
https://c1.staticflickr.com/9/8631/1...4bb7c59e_c.jpg

I'll run another series of tests, and see if any of that made
a difference.

makolber wrote, on Mon, 22 Dec 2014 10:24:18 -0800:

I suggest you read my previous post that explains how the flame sensor
circuit works.
You can lead a horse to water......
Mark

Hi Mark,
I had read your suggestion and followed it as much as possible.

There is a flame sensor, and a hot igniter, which are located he
https://c1.staticflickr.com/9/8651/1...7fe7ca9f_c.jpg

I don't know yet how to physically 'test' them, but they do not appear
to be damaged. There is absolutely no water, and the ground appears
good but I need to run more tests on ground to be doubly sure.

The good news is that, after wiggling everything and opening all the
vents, and replacing the batteries, I called for heat just now:
https://c4.staticflickr.com/8/7553/1...1d83ee2a_b.jpg

First the first time all winter, the igniter lit after the blower
motor ran for a minute or so!
https://c4.staticflickr.com/8/7566/1...a8d7692c_c.jpg

Then, for the first time, the flame and igniter went on:
https://c4.staticflickr.com/8/7554/1...38cbbba7_c.jpg

Then, just the flame went on, for about 10 seconds or so:
https://c4.staticflickr.com/8/7550/1...b9901d66_c.jpg

This happened three times, in quick succession, and then the furnace
went back to the blinking.

I will post the blinking video separately, as it seems to be
blinking a different code now.

"Danny D." wrote in message
...
makolber wrote, on Mon, 22 Dec 2014 10:24:18 -0800:

I suggest you read my previous post that explains how the flame sensor
circuit works.
You can lead a horse to water......
Mark

Hi Mark,
I had read your suggestion and followed it as much as possible.

There is a flame sensor, and a hot igniter, which are located he
https://c1.staticflickr.com/9/8651/1...7fe7ca9f_c.jpg

I don't know yet how to physically 'test' them, but they do not appear
to be damaged. There is absolutely no water, and the ground appears
good but I need to run more tests on ground to be doubly sure.

The good news is that, after wiggling everything and opening all the
vents, and replacing the batteries, I called for heat just now:
https://c4.staticflickr.com/8/7553/1...1d83ee2a_b.jpg

First the first time all winter, the igniter lit after the blower
motor ran for a minute or so!
https://c4.staticflickr.com/8/7566/1...a8d7692c_c.jpg

Then, for the first time, the flame and igniter went on:
https://c4.staticflickr.com/8/7554/1...38cbbba7_c.jpg

Then, just the flame went on, for about 10 seconds or so:
https://c4.staticflickr.com/8/7550/1...b9901d66_c.jpg

This happened three times, in quick succession, and then the furnace
went back to the blinking.

I will post the blinking video separately, as it seems to be
blinking a different code now.

Now that all that went on, it might be time to check the air flow switch.
It will be something after the blower mounted on the air chamber. It is a
switch that will probably show open and when you have air flow it will
close. If it does show open, and never closes when the blower starts up,
you have low air flow. Either the blower is not turning or the switch could
be bad. If it shows open, hook the two wires together and see if the
furnace stays running. Or place your meter across the wires and see if they
stay closed. You can probably go to ground from one of the contacts and one
side will always have voltage and the other one will not. Get on the one
without the voltage and see if it ever gets the voltage.



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Stormin Mormon wrote, on Mon, 22 Dec 2014 11:26:40 -0500:

With that clogged air filter, I'd be thinking bad thermal limit switch.
I replaced one this year in my own furnace, and one about a week later
for a customer.

Partial success!

After all the fiddling, I'm finally getting the thermal igniter to
ignite, and the flames go on three times, and then shut off, so,
that's a partial success, I guess.

First, the LED was solid red for a minute or so:
https://www.flickr.com/photos/98287134@N02/16082030575/

But then, it quickly switched to what appeared to be a code #12:
https://www.flickr.com/photos/98287134@N02/16081998125/

Then, the flames went on three times and then off within seconds
with a resulting LED blinking code of what appears to be #34:
https://www.flickr.com/photos/98287134@N02/16081950225/

Given all those inconsistencies within the span of 15 minutes,
I'm not sure if things are changing or if there are more than
one problem or if the thing just needs to settle down, because
those blink codes are changing depending on what is happening
with the blower.
https://c4.staticflickr.com/8/7505/1...4f42e6c5_c.jpg

The gas valve is definitely turned on, and there is plenty of
gas on the stove and in the 500 gallon propane tank.
https://c4.staticflickr.com/8/7508/1...4311f464_k.jpg

I will doublecheck that the metal case is grounded, and, I will
sand or steel wool the flame sensor and check the amperage if my
Fluke 75 can get down that low.

34: Ignition proving failu Control will try three more times
before a lockout #14 occurs. If flame signal lost after trial
for ignition period, blower will come on for 90-second
recycle delay. Check for:
- Oxide buildup on flame sensor (clean with fine sandpaper)
- Proper flame sense microamps (0.5microamps DC minimum)
- Gas valve turned off (manual shutoff valve, low inlet gas pressure)
- Green wire MUST be connected to furnace sheet metal
- Inadequate flame carryover or rough ignition

14: Ignition Lockout: Control will auto-reset after three hours.
Refer to #34.

12: Blower on after power up: (115V or 24V) Blower runs for 90
seconds, if unit is powered up during a call for heat
(R-W closed).
https://c4.staticflickr.com/8/7545/1...d3f7f629_c.jpg

On Monday, December 22, 2014 2:39:04 PM UTC-5, Ralph Mowery wrote:
"Danny D." wrote in message
...
makolber wrote, on Mon, 22 Dec 2014 10:24:18 -0800:

I suggest you read my previous post that explains how the flame sensor
circuit works.
You can lead a horse to water......
Mark

Hi Mark,
I had read your suggestion and followed it as much as possible.

There is a flame sensor, and a hot igniter, which are located he
https://c1.staticflickr.com/9/8651/1...7fe7ca9f_c.jpg

I don't know yet how to physically 'test' them, but they do not appear
to be damaged. There is absolutely no water, and the ground appears
good but I need to run more tests on ground to be doubly sure.

The good news is that, after wiggling everything and opening all the
vents, and replacing the batteries, I called for heat just now:
https://c4.staticflickr.com/8/7553/1...1d83ee2a_b.jpg

First the first time all winter, the igniter lit after the blower
motor ran for a minute or so!
https://c4.staticflickr.com/8/7566/1...a8d7692c_c.jpg

Then, for the first time, the flame and igniter went on:
https://c4.staticflickr.com/8/7554/1...38cbbba7_c.jpg

Then, just the flame went on, for about 10 seconds or so:
https://c4.staticflickr.com/8/7550/1...b9901d66_c.jpg

This happened three times, in quick succession, and then the furnace
went back to the blinking.

I will post the blinking video separately, as it seems to be
blinking a different code now.

Now that all that went on, it might be time to check the air flow switch.
It will be something after the blower mounted on the air chamber. It is a
switch that will probably show open and when you have air flow it will
close. If it does show open, and never closes when the blower starts up,
you have low air flow. Either the blower is not turning or the switch could
be bad. If it shows open, hook the two wires together and see if the
furnace stays running.

It's not an air handler blower issue. He gets the flashing trouble
indication as soon as power is applied, without any call for heat, without
the furnace firing, without the blower ever starting.

"trader_4" wrote in message
...
It's not an air handler blower issue. He gets the flashing trouble
indication as soon as power is applied, without any call for heat, without
the furnace firing, without the blower ever starting.


He was getting that flashing , but he just said the heater tried to start
after he did all the resetting and checking later on.

The heater could have came on at the very start and failed. This could have
tripped a safety device and he finally reset it, only to have it fault again
on the restart attempt.



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On Monday, December 22, 2014 4:55:35 PM UTC-5, Ralph Mowery wrote:
"trader_4" wrote in message
...
It's not an air handler blower issue. He gets the flashing trouble
indication as soon as power is applied, without any call for heat, without
the furnace firing, without the blower ever starting.


He was getting that flashing , but he just said the heater tried to start
after he did all the resetting and checking later on.

Again, "tried to start", is not an air handler blower problem. If the
blower failed, there were clogged filters, etc, the furnace would fire up.
run for several minutes, then shut off with a failure code.


The heater could have came on at the very start and failed. This could have
tripped a safety device and he finally reset it, only to have it fault again
on the restart attempt.



Two problems with that:

1 - It has continous blinking, ie abnormal LED as soon as power is restored. It's not firing and then reporting a problem.

2 - If it fired at the very start and failed, it's also not a blower
problem. The blower typically comes on about 2 mins into the whole
startup. For it to reach an over temp and shut down, would require a
lot longer.





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trader_4 wrote:
On Monday, December 22, 2014 4:55:35 PM UTC-5, Ralph Mowery wrote:
"trader_4" wrote in message
...
It's not an air handler blower issue. He gets the flashing trouble
indication as soon as power is applied, without any call for heat, without
the furnace firing, without the blower ever starting.


He was getting that flashing , but he just said the heater tried to start
after he did all the resetting and checking later on.

Again, "tried to start", is not an air handler blower problem. If the
blower failed, there were clogged filters, etc, the furnace would fire up.
run for several minutes, then shut off with a failure code.


The heater could have came on at the very start and failed. This could have
tripped a safety device and he finally reset it, only to have it fault again
on the restart attempt.



Two problems with that:

1 - It has continous blinking, ie abnormal LED as soon as power is restored. It's not firing and then reporting a problem.

2 - If it fired at the very start and failed, it's also not a blower
problem. The blower typically comes on about 2 mins into the whole
startup. For it to reach an over temp and shut down, would require a
lot longer.





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Hi,
First, I'd just clean the flame sensor to get one thing out of the way.
I never ran into failed sensor but dirty one which did not work well.
Rubbing it with emery cloth always made it work again.

Ralph Mowery wrote, on Mon, 22 Dec 2014 14:43:24 -0500:

Now that all that went on, it might be time to check the air flow
switch. It will be something after the blower mounted on the air
chamber. It is a switch that will probably show open and when you have
air flow it will close. If it does show open, and never closes when the
blower starts up, you have low air flow. Either the blower is not
turning or the switch could be bad. If it shows open, hook the two
wires together and see if the furnace stays running. Or place your
meter across the wires and see if they stay closed. You can probably go
to ground from one of the contacts and one side will always have voltage
and the other one will not. Get on the one without the voltage and see
if it ever gets the voltage.

Do you think this might be the air-flow switch, bolted into the side
of the air chamber?
https://c4.staticflickr.com/8/7527/1...d908b870_b.jpg

I tested it and it seems to be a short (which is probably what it
is supposed to be).
https://c4.staticflickr.com/8/7540/1...18ee847c_b.jpg

It might be a temperature switch though... or a fusible link?
https://c4.staticflickr.com/8/7498/1...4fb55b63_b.jpg

Tony Hwang wrote, on Mon, 22 Dec 2014 15:58:34 -0700:

First, I'd just clean the flame sensor to get one thing out of the way.
I never ran into failed sensor but dirty one which did not work well.
Rubbing it with emery cloth always made it work again.

The flame sensor is supposed to have 50 microamps, but I
couldn't measure that low with my Fluke 75 DMM:
https://c4.staticflickr.com/8/7463/1...2757e870_b.jpg

So I removed the flame sensor to take a look at its condition:
https://c4.staticflickr.com/8/7475/1...8647f174_b.jpg

That flame sensor was in surprisingly good shape, as is everything:
https://c4.staticflickr.com/8/7517/1...71745c49_b.jpg

Even so, I steel wooled the small amount of oxide, just to be safe:
https://c4.staticflickr.com/8/7539/1...d5cf70c5_b.jpg

On 12/22/2014 1:10 PM, Danny D. wrote:
Stormin Mormon wrote, on Mon, 22 Dec 2014 12:49:48 -0500:

But, I'll check it - and report back - with pictures.
We'd expect nothing less from the professional you are.

I gathered the testing equipment:
https://c4.staticflickr.com/8/7541/1...ea2b8a1c_b.jpg

I turned off the wall switch (it's turned on in this pic):
https://c4.staticflickr.com/8/7498/1...481232cf_b.jpg

I removed the cover of the inlex box from the BX cable:
https://c4.staticflickr.com/8/7511/1...594e782c_b.jpg

I separated the hot (black), neutral (white) & ground (green):
https://c4.staticflickr.com/8/7573/1...1a9fd07a_b.jpg

Turning power on, I tested neutral to ground at 0 volts AC:
https://c4.staticflickr.com/8/7533/1...a061993a_b.jpg

Turning power on, I tested hot to ground at nominally 120VAC.
https://c1.staticflickr.com/9/8638/1...8709828b_b.jpg

Turning power on, I tested hot to neutral at nominally 120VAC.
https://c4.staticflickr.com/8/7490/1...7fb5ddc8_b.jpg

I turned the power off, and reconnected the wires as before.

If the power is reversed, it's not at the inlet BX cable
connection to the unit.

What I mostly want to find is the big red button that says
"reset", but I don't see it. I see a bunch of smaller limit
resets, all of which I've pressed already.

Sounds properly polaraized. The big reset is usually
to switch off the AC power for several seconds.

--
..
Christopher A. Young
Learn about Jesus
www.lds.org
..

Stormin Mormon wrote, on Mon, 22 Dec 2014 11:24:38 -0500:

Black is hot, white is neutral, and green is ground. You test at the
little box I mentioned earlier.

I double checked all the grounds, and they're good.
https://c1.staticflickr.com/9/8597/1...62d59465_z.jpg

On 12/22/2014 1:51 PM, Danny D. wrote:
trader_4 wrote, on Mon, 22 Dec 2014 08:37:51 -0800:

No, they are talking about polarity reversed at the incoming AC,
ie hot and neutral. How would you ever get DC reversed on the circuit
board?

The incoming power, at least at the BX cable coming into the furnace,
is not reversed, but, clearly "something" is wrong, so I do
appreciate the advice as to what to look for.

A few things I did in the meantime, which "may" have changed the
situation is that I opened up all the vents in the house, most
of which had been closed for some reason (almost certainly since
last winter), which means the vent airflow was certainly stifled.

I opened all the suckers:
https://c4.staticflickr.com/8/7563/1...ca4af62b_b.jpg

And all the blowers:
https://c4.staticflickr.com/8/7478/1...a422228b_b.jpg

And, I ascertained that there is no V-shaped filter in the top
(left) side of the furnace itself:
https://c4.staticflickr.com/8/7491/1...8312f3fe_c.jpg

This lack of v-shaped filters is apparently normal, as it is
described on the furnace cover sticker, which says:
"Horizontal furnace: Filters are located external of furnace.
Consult installer for location."
https://c4.staticflickr.com/8/7474/1...0f645731_c.jpg

Interestingly, since most of the vents were closed, I might assume
the furnace had shut off due to lack of air, but I can't find
what the sticker also says is the "RESET" button:
"Auxiliary limit control may be located on blower housing or
top of furnace. To RESET, push button on control firmly.
Refer to USERS MANUAL for more information. Call qualified
serviceman if failure continues."

Also, the sticker talks about a "fusible link", which I also
haven't found yet:
https://c1.staticflickr.com/9/8575/1...a6bf6b65_c.jpg
"This furnace is equipped with a fusible element or manual reset
limit switch in burnder compartment and/or draft diverter to
protect against overheat conditions that can result from
inadequate combustion air supply or blocked vent conditions."

Just in case, I hit all the reset buttons I could find, starting
with the two manual limit switches:
https://c4.staticflickr.com/8/7496/1...acc7329a_c.jpg

When I press the brown button on the manual limit switch, nothing
happens (I had expected a spring-loaded type of interaction):
https://c4.staticflickr.com/8/7490/1...550d1ee2_c.jpg

I pressed the brown button on the blocked vent tube switch:
https://c4.staticflickr.com/8/7580/1...19b8f191_c.jpg

There were no buttons on the flame sensor and hot surface igniter,
so, I merely wiggled the wires to ensure they were on snugly:
https://c1.staticflickr.com/9/8651/1...7fe7ca9f_c.jpg

I suspect this is the backside of the fusible link, which likewise,
I wiggled the wires to ensure they were on tightly:
https://c4.staticflickr.com/8/7498/1...4fb55b63_b.jpg

I also flipped the on-off switch, on the gas valve itself, a few times:
https://c1.staticflickr.com/9/8681/1...d011aced_c.jpg

I also wiggled all the wires and connections on the control board:
https://c1.staticflickr.com/9/8631/1...4bb7c59e_c.jpg

I'll run another series of tests, and see if any of that made
a difference.




Might have been someone, suggested low air
flow, and a bad limit switch. Trader, was
that you?

--
..
Christopher A. Young
Learn about Jesus
www.lds.org
..

Stormin Mormon wrote, on Mon, 22 Dec 2014 19:37:57 -0500:

Sounds properly polaraized. The big reset is usually to switch off the
AC power for several seconds.

While I have an AC on/off switch:
https://c4.staticflickr.com/8/7498/1...481232cf_b.jpg

I don't seem to have that big red button inside the blower compartment:
https://c4.staticflickr.com/8/7491/1...8312f3fe_z.jpg

Yet, the manual implies that there can be an "AUXILIARY LIMIT SWITCH
(WHEN USED)"; but mine doesn't seem to have that switch.
https://c4.staticflickr.com/8/7541/1...4c0debcd_z.jpg

On 12/22/2014 2:43 PM, Ralph Mowery wrote:

Now that all that went on, it might be time to check the air flow switch.
It will be something after the blower mounted on the air chamber. It is a
switch that will probably show open and when you have air flow it will
close. If it does show open, and never closes when the blower starts up,
you have low air flow. Either the blower is not turning or the switch could
be bad. If it shows open, hook the two wires together and see if the
furnace stays running. Or place your meter across the wires and see if they
stay closed. You can probably go to ground from one of the contacts and one
side will always have voltage and the other one will not. Get on the one
without the voltage and see if it ever gets the voltage.



With a new filter, and open vents, should
be much improved air flow. Lets see who
spots the non sequitor.


--
..
Christopher A. Young
Learn about Jesus
www.lds.org
..

On 12/22/2014 7:26 PM, Danny D. wrote:

Do you think this might be the air-flow switch, bolted into the side
of the air chamber?
https://c4.staticflickr.com/8/7527/1...d908b870_b.jpg

I tested it and it seems to be a short (which is probably what it
is supposed to be).
https://c4.staticflickr.com/8/7540/1...18ee847c_b.jpg

It might be a temperature switch though... or a fusible link?
https://c4.staticflickr.com/8/7498/1...4fb55b63_b.jpg


The thing with two rods, sleeves, and
what looks like a coin cell, is a thermal
cutout. It "should" be self resetting.
Continuity is good. Does not measure air
flow.

--
..
Christopher A. Young
Learn about Jesus
www.lds.org
..

Stormin Mormon wrote, on Mon, 22 Dec 2014 20:16:27 -0500:

The thing with two rods, sleeves, and what looks like a coin cell, is a
thermal cutout. It "should" be self resetting. Continuity is good. Does
not measure air flow.

Seems reasonable.

I don't know what measures air flow.

This is a "pressure sensor", with a black tube connected to the air
chamber; but I don't know how to test it yet:
https://c4.staticflickr.com/8/7516/1...46b2ae86_c.jpg

Stormin Mormon wrote, on Mon, 22 Dec 2014 19:39:38 -0500:

Might have been someone, suggested low air flow, and a bad limit
switch. Trader, was that you?

Seems reasonable.

My hypothesis, at the moment, is that all the vents where shut
which (maybe) caused a "limit switch" to open up?

If only I could turn that limit switch back on.

I wish I could find a "master reset" which doesn't seem
to exist. I've pressed all the limit switch buttons I could
find already.

Here's the latest video after cleaning the flame sensor and
hooking up the DMM in DC amps mode at the 300ma range with
the flame sensor hooked in series with the DMM:
https://www.flickr.com/photos/98287134@N02/15464227533/

As before, the blower started up & then the induced draft motor
spun up, & then the igniter lit up orange, & then there were
flames which soon shut down. The flames happened three times,
all the while the LED blinked #34. When the flames died the
third time, the furnace shut down & the LED blinked #14.
https://c4.staticflickr.com/8/7521/1...32e0de5a_z.jpg

34 IGNITION PROVING FAILURE
- Control will try three more times before a lockout #14 occurs.
If flame signal lost after trial for ignition period, blower will
come on for 90 second recycle delay. Check for:
- Oxide buildup on flame sensor (clean with fine sandpaper).
- Proper flame sense microamps (.5 microamps D.C. minimum).
- Gas valve turned off. - Manual shut-off valve. - Low inlet gas pressure.
- Green wire MUST be connected to furnace sheet metal.
- Inadequate flame carryover or rough ignition.

14 IGNITION LOCKOUT
- Control will auto-reset after three hours.
Refer to #34.

Stormin Mormon wrote, on Mon, 22 Dec 2014 20:11:18 -0500:

With a new filter, and open vents, should be much improved air
flow. Lets see who spots the non sequitor.

I'm not sure I understand ...

non sequitor === an inference that does not follow from the premises;
specifically : a fallacy resulting from a simple conversion of a
universal affirmative proposition or from the transposition of a
condition and its consequent.
- a statement (as a response) that does not follow logically from or is
not clearly related to anything previously said.

Anyway, I did *try* to run the "component test" as described he
https://c4.staticflickr.com/8/7521/1...32e0de5a_c.jpg

COMPONENT TEST
To initiate the component test sequence,shut OFF the room
thermostat or disconnect the "R" thermostat lead. Briefly short
the TEST terminal to the Com 24V terminal. Status LED will flash
code and then turn ON the inducer motor. The inducer motor will
run for the entire component test. The hot surface ignitor,
blower motor-heat speed, and blower motor-cool speed will be
turned ON for 10-15 seconds each".

I first removed the RED wire from the (R) terminal block screw,
but when I held down the door switch and then at the same time I
touched the COM terminal to the TEST terminal, nothing happened:
https://c4.staticflickr.com/8/7554/1...08719d7e_b.jpg

So, I belatedly realized they must be talking about removing the
RED (R) terminal at the thermostat itself, so, put back the Red
wire onto the (R) terminal at the furnace, and then went down to
the thermostat and removed the two red wires from that thermostat.

Then, back up at the furnace, I added this orange wire to the COM
terminal so that I could hold down the door switch and then touch
the orange wire momentarily to the TEST blade on the control board:
https://c4.staticflickr.com/8/7560/1...b61ec375_c.jpg

I'm not exactly sure what happened in this component test, but,
a bunch of things went on, and that was it. For example, the
inducer motor ran, and the igniter lit for a few seconds, but,
I didn't see anything else happen that told me any data.

Maybe I missed something in the so-called "component" test?

Danny D. wrote, on Fri, 19 Dec 2014 23:56:58 +0000:

Debugging suggestions are requested, and very helpful. Thanks!

Here's where the Bryant 373LAV horizontal furnace stands tonight.

Blower starts, inducer motor starts, igniter starts, flame starts,
flame shuts down. Three times the igniter ignites the flame but
three times, the flame shuts down within seconds.

All the while it displays code #34.
At the end of the sequence, it shuts down and displays code #14.

Video:
https://www.flickr.com/photos/98287134@N02/15464227533/

Schematic:
https://www.flickr.com/photos/98287134@N02/15460746143/

Codes:
https://www.flickr.com/photos/98287134@N02/16083106532/

34 IGNITION PROVING FAILURE
- Control will try three more times before a lockout #14 occurs.
If flame signal lost after trial for ignition period, blower will
come on for 90 second recycle delay. Check for:
- Oxide buildup on flame sensor (clean with fine sandpaper).
- Proper flame sense microamps (.5 microamps D.C. minimum).
- Gas valve turned off. - Manual shut-off valve. - Low inlet gas pressure.
- Green wire MUST be connected to furnace sheet metal.
- Inadequate flame carryover or rough ignition.

14 IGNITION LOCKOUT
- Control will auto-reset after three hours.
Refer to #34.

On Monday, December 22, 2014 8:52:22 PM UTC-5, Danny D. wrote:
Danny D. wrote, on Fri, 19 Dec 2014 23:56:58 +0000:

Debugging suggestions are requested, and very helpful. Thanks!

Here's where the Bryant 373LAV horizontal furnace stands tonight.

Blower starts, inducer motor starts, igniter starts, flame starts,
flame shuts down. Three times the igniter ignites the flame but
three times, the flame shuts down within seconds.

All the while it displays code #34.
At the end of the sequence, it shuts down and displays code #14.

Video:
https://www.flickr.com/photos/98287134@N02/15464227533/

Schematic:
https://www.flickr.com/photos/98287134@N02/15460746143/

Codes:
https://www.flickr.com/photos/98287134@N02/16083106532/

34 IGNITION PROVING FAILURE
- Control will try three more times before a lockout #14 occurs.
If flame signal lost after trial for ignition period, blower will
come on for 90 second recycle delay. Check for:
- Oxide buildup on flame sensor (clean with fine sandpaper).
- Proper flame sense microamps (.5 microamps D.C. minimum).
- Gas valve turned off. - Manual shut-off valve. - Low inlet gas pressure.
- Green wire MUST be connected to furnace sheet metal.
- Inadequate flame carryover or rough ignition.

14 IGNITION LOCKOUT
- Control will auto-reset after three hours.
Refer to #34.

Ok, so now the question that might shed some light on what's going on
is, what changed that allowed the furnace to get this far? Previously,
it would come up with a flashing LED trouble indication as soon as power
was put on, without firing at all. Now, it's firing, then shutting down
because it thinks it hasn't lit.

I think that may be relevant, because initially you had continous LED
flashes that the chart says corresponds to reversed polarity. While
the polarity isn't reveresed, I wonder if it will also give that code
if the ground is missing? I ask that because the flame sensor is
single wire and depends on a ground path back to the controller board.
Is it possible there is a bad ground connection between the controller
board and the furnace metal?

Other than that, the most obvious and direct possibility is that the
flame sensor is bad. If you'd had this code, this behavior from the
beginning, that would be the logical place to start. But what's odd
is how it behaved very differently initially, unless that was something
to do with you having the safety switch open, how you were starting it,
etc.

trader_4 wrote, on Tue, 23 Dec 2014 04:44:15 -0800:

Ok, so now the question that might shed some light on what's going on
is, what changed that allowed the furnace to get this far? Previously,
it would come up with a flashing LED trouble indication as soon as power
was put on, without firing at all. Now, it's firing, then shutting down
because it thinks it hasn't lit.

I agree with you.

The manual says:
"NOTE: If the polarity is not correct, the STATUS LED on the
control center will flash rapidly and prevent the furnace from
heating. The control system also requires an earth ground for
proper operation of the control and flame sensing."

So, *both* the old and new LED indications point to a suspected
lack of "earth" ground (among other things).

Plus, the constant flashing stopped just about when I started testing
the power connections (although, I didn't *change* anything). I
wiggled everything. But I left the wiring as it was before.

Yet, suddenly, it stopped flashing constantly, and, instead, the
error migrated from a power problem to short cycling (which now
implicates either the flame sensor or the flame sensor control
circuit).

Yet, the flame sensor has only one wire, so, ground is clearly
the case.

I think that may be relevant, because initially you had continous LED
flashes that the chart says corresponds to reversed polarity. While the
polarity isn't reveresed, I wonder if it will also give that code if the
ground is missing? I ask that because the flame sensor is single wire
and depends on a ground path back to the controller board. Is it
possible there is a bad ground connection between the controller board
and the furnace metal?

I'm thinking the same thing. A bad ground could cause the flame proving
electrode not to have its requisite 5 microamps to 6 microamps. In the
schematic, there are two "Note #5" comments, each next to the "GV" which
is the gas valve

Note #5 says:
"5. This wire must be connected to furnace sheetmetal for control
to detect flame."
https://www.flickr.com/photos/98287134@N02/15460746143/

I'll need to check that, remove it, sand it, clean it, & re-test.

I suspect ground is critical for the flame-sensing circuit, because
the DC current is only 5 or 6 microamperes, which is so low, I'm
going to have to figure out *how* to test it using coils of wire
wrapped around an ammeter.

Other than that, the most obvious and direct possibility is that the
flame sensor is bad. If you'd had this code, this behavior from the
beginning, that would be the logical place to start. But what's odd is
how it behaved very differently initially, unless that was something to
do with you having the safety switch open, how you were starting it,
etc.

Looking at the troubleshooting flow chart, it does now imply that
either the flame proving electrode is bad, or that the control to
that flame sensor is bad.
https://www.flickr.com/photos/98287134@N02/15894320489/

I agree with you:
1. Today I will clean all the grounds.
2. I will check that "Note #5" wire listed in the schematic.
3. I will re-clean the flame sensing electrode (just in case).
4. I will figure out how to measure 5 or 6 microamperes
(and it can be as low as half a microampere).

Danny D. wrote, on Tue, 23 Dec 2014 13:21:56 +0000:

So, *both* the old and new LED indications point to a suspected lack of
"earth" ground (among other things).

Found a service manual online, by the way:
http://manualslib.com/manual/22390/B...es-373lav.html

Danny D. wrote, on Tue, 23 Dec 2014 14:36:38 +0000:

Found a service manual online, by the way:
http://manualslib.com/manual/22390/B...es-373lav.html

Here's a better link to the service manual so you can
see the schematic and troubleshooting flowchart:
http://dms.hvacpartners.com/docs/100...00/SP04-62.pdf

On Tuesday, December 23, 2014 9:37:04 AM UTC-5, Danny D. wrote:
Danny D. wrote, on Tue, 23 Dec 2014 13:21:56 +0000:

So, *both* the old and new LED indications point to a suspected lack of
"earth" ground (among other things).


If the ground is affecting the flame sensor, then it't the ground path
from the metal cabinet/frame of the furnace to the control board. That's
where I'd be looking. There must be a ground wire that goes from the control
board to the frame and the frame is also grounded to the incoming AC.

it is difficult to measure the 5 uA using a VOM.

I think you are on the right track.

Check all the grounds
This means the controller ground to the AC supply and ALSO the furnace chassis ground to the AC supply.

Check that the flame sensor insulator is clean so that there is no partial short to ground of the flame sensor output whick is a very small DC voltage or current realtive to funrace chassis ground.

Check that the flame sensor probe is not very dirty but I don't see how that would casue the original symptom, but culd casue the symptoms you have now.

Check that the flame sensor probe does not touch metal but is properly touching the flame.

The flame sensor probe acts as a tiny battery and the controller needs to sense that current. THe flame sensor current is relative to the furnce ground which needs to be connectd to the AC ground and to the controller ground.. I guess also make sure the burner jets are also grounded to the chassis. The flame is grounded to the burner jets actually.

Mark

Looking up videos on troubleshooting a Bryant 373LAV flame sensor,
these guys clean it with a brand new five-dollar bill:
https://www.youtube.com/watch?featur...qL4lnk#t=13 0

This looks like a similar furnace to mine, with a similar issue,
and this guy does not recommend cleaning the flame sensor:
https://www.youtube.com/watch?featur...KsZhc0#t=36 6

After replacing the flame sensor, he shows the whole cycle:
https://www.youtube.com/watch?featur...KsZhc0#t=95 0

These guys use #0000 fine steel wool to clean the flame sensor:
https://www.youtube.com/watch?featur...gBB_R4#t=34 4
https://www.youtube.com/watch?featur...qlGfZv8Es#t=59

All say not to touch the sensor with fingers, which I didn't
know when I first had cleaned it.

But, interestingly, *all* (of those) simply clean or replace the flame sensor
without *any* of them testing it for the 5 or 6 uamps of control current.
(I'll google separately for videos *testing* the flame sensor circuit
but this is already long.)

Normally, I test things before replacing them, but, none of the
technicians in the youtube videos I've found bothered to test it
before replacing it.

Even so, I might buy a spare flame sensor and igniter, and keep
it next to the furnace. Any suggestions as to good suppliers?