Central AC quit
 

Seems to be 120vac from red to ground and 120vac from black to ground but no
voltage between red and black, which should be 240vac. Reading was taken at
the external dissconnect. What might cause this?

Thanks,
S

Central AC quit
 

On 07/01/2017 07:08 AM, Sherlock.Homes wrote:
Seems to be 120vac from red to ground and 120vac from black to ground but no
voltage between red and black, which should be 240vac. Reading was taken at
the external dissconnect. What might cause this?

Thanks,
S


If red is L1 and black is L2, it seems like you don't know how to use a
volt meter properly.

Central AC quit
 

On Saturday, July 1, 2017 at 6:09:00 AM UTC-5, Sherlock.Homes wrote:
Seems to be 120vac from red to ground and 120vac from black to ground but no
voltage between red and black, which should be 240vac. Reading was taken at
the external dissconnect. What might cause this?

Thanks,
S


One leg is dead and you're reading voltage through the crankcase heater. make sure the disconnect is off before checking the voltage. Read the voltages at the circuit breaker feeding the external disconnect. One side could be tripped or there is a bad connection. Turn the breaker off forcefully to make sure it clicks and resets if it tripped before. Sometimes, a 2 pole breaker will trip and if you don't use enough force when you turn it off, one side may not reset. I've seen it happen more than once. ヽ(ヅ)ノ

[8~{} Uncle Broken Monster

Central AC quit
 

In article ,
says...

On 07/01/2017 07:08 AM, Sherlock.Homes wrote:
Seems to be 120vac from red to ground and 120vac from black to ground but no
voltage between red and black, which should be 240vac. Reading was taken at
the external dissconnect. What might cause this?

Thanks,
S


If red is L1 and black is L2, it seems like you don't know how to use a
volt meter properly.

If the disconnect is not thrown , UM could be right, something is
letting the voltage through to the other side.

If the disconnect is thrown, then one side is the real voltage, and the
other side is probably the 'phantom' voltage caused by the high
impedance of the meter picking up the induced voltage on the wiring.

One side could be open somewhere.To find out which, take a light bulb,
anywhere from a couple of watts up to 100 watts and put across the line
from L1 to neutral and then L2 to neutral. Do that on the 'hot' side of
the disconnect.

Could be the breaker is bad, needs to be reset, or if fuses are used,
one bad fuse.

Central AC quit
 

On Sat, 1 Jul 2017 07:38:41 -0400, Detective Marcus Bell
wrote:

On 07/01/2017 07:08 AM, Sherlock.Homes wrote:
Seems to be 120vac from red to ground and 120vac from black to ground but no
voltage between red and black, which should be 240vac. Reading was taken at
the external dissconnect. What might cause this?

Thanks,
S


If red is L1 and black is L2, it seems like you don't know how to use a
volt meter properly.
Sounds to me like someone moved the 2 pole breaker and it's not on
both sides of the line. Both black and red are on the same side of the
service.

Sherlock Holmes, father of John Holmes, talks about "Central AC went out and gawddamit all!"
 

On Sat, 1 Jul 2017 08:40:20 -0700, "fake vet Colon Edmund J. Burke"
wrote:

On 7/1/2017 4:08 AM, Sherlock.Homes wrote:
Seems to be 120vac from red to ground and 120vac from black to ground but no
voltage between red and black, which should be 240vac. Reading was taken at
the external dissconnect. What might cause this?


Yer mammy's lips on my dipstick, maybe?

YER mammy's moulie lips on EVERYONE'S dipstick, KKKoloon!

--
Illuc nisi Dei gratia.vadam.

Tu [sic] es [sic] mulieri [sic] nequam [sic] (KKKoloon's 'Latin' LOL)

Central AC quit
 

On Saturday, July 1, 2017 at 7:09:00 AM UTC-4, Sherlock.Homes wrote:
Seems to be 120vac from red to ground and 120vac from black to ground but no
voltage between red and black, which should be 240vac. Reading was taken at
the external dissconnect. What might cause this?

Thanks,
S

Is the disconnect open or closed?

Central AC quit
 

On 07/01/2017 07:13 AM, Uncle Monster wrote:
On Saturday, July 1, 2017 at 6:09:00 AM UTC-5, Sherlock.Homes wrote:
Seems to be 120vac from red to ground and 120vac from black to ground but no
voltage between red and black, which should be 240vac. Reading was taken at
the external dissconnect. What might cause this?

Thanks,
S

One leg is dead and you're reading voltage through the crankcase heater. make sure the disconnect is off before checking the voltage.

The central crankcase heater?

Central AC quit
 

On 07/01/2017 09:13 AM, Uncle Monster wrote:
One leg is dead and you're reading voltage through the crankcase heater.


Nice catch!

Central AC quit
 

On Saturday, July 1, 2017 at 1:31:49 PM UTC-4, Trumpster wrote:
On 07/01/2017 09:13 AM, Uncle Monster wrote:
One leg is dead and you're reading voltage through the crankcase heater.


Nice catch!

Excellent call uncle ace troubleshooter monster.

Central AC quit
 

On Saturday, July 1, 2017 at 11:45:40 AM UTC-5, rbowman wrote:
On 07/01/2017 07:13 AM, Uncle Monster wrote:
On Saturday, July 1, 2017 at 6:09:00 AM UTC-5, Sherlock.Homes wrote:
Seems to be 120vac from red to ground and 120vac from black to ground but no
voltage between red and black, which should be 240vac. Reading was taken at
the external dissconnect. What might cause this?

Thanks,
S

One leg is dead and you're reading voltage through the crankcase heater.. make sure the disconnect is off before checking the voltage.

The central crankcase heater?


On a split system, there is a crankcase heater that's hooked across the 240 vac line at the contactor and is always energized. If one leg of the 240 volt supply is disconnected for some reason such as a defective breaker, a loose or burned off connection anywhere past the breaker, a high impedance meter will read 120 vac to ground/neutral from each side because one leg is feeding through the crankcase heater which is nothing more than a big resistor. A crankcase heater is either a cartridge in a well in the crankcase or a strap that resembles a big hose clamp with a flexible heating element that wraps around the base of the compressor. To go off on a tangent, some systems supply a low current to the motor windings to keep the compressor warm but you don't run across them very often. ヽ(ヅ)ノ

https://en.wikipedia.org/wiki/Crankcase_heater

https://highperformancehvac.com/cran...s-compressors/

[8~{} Uncle Cranked Monster

Central AC quit
 

On 07/01/2017 03:18 PM, Uncle Monster wrote:
On a split system, there is a crankcase heater that's hooked across the 240 vac line at the contactor and is always energized. If one leg of the 240 volt supply is disconnected for some reason such as a defective breaker, a loose or burned off connection anywhere past the breaker, a high impedance meter will read 120 vac to ground/neutral from each side because one leg is feeding through the crankcase heater which is nothing more than a big resistor. A crankcase heater is either a cartridge in a well in the crankcase or a strap that resembles a big hose clamp with a flexible heating element that wraps around the base of the compressor. To go off on a tangent, some systems supply a low current to the motor windings to keep the compressor warm but you don't run across them very often.

Shows what I know about central A/C. But then, I've never had A/C,
central or otherwise, in anything but cars. By choosing not to live in
Alabamistan I've avoided a number of things. 300% humidity, chiggers,...

Central AC quit
 

On Saturday, July 1, 2017 at 8:21:46 PM UTC-5, rbowman wrote:
On 07/01/2017 03:18 PM, Uncle Monster wrote:
On a split system, there is a crankcase heater that's hooked across the 240 vac line at the contactor and is always energized. If one leg of the 240 volt supply is disconnected for some reason such as a defective breaker, a loose or burned off connection anywhere past the breaker, a high impedance meter will read 120 vac to ground/neutral from each side because one leg is feeding through the crankcase heater which is nothing more than a big resistor. A crankcase heater is either a cartridge in a well in the crankcase or a strap that resembles a big hose clamp with a flexible heating element that wraps around the base of the compressor. To go off on a tangent, some systems supply a low current to the motor windings to keep the compressor warm but you don't run across them very often.

Shows what I know about central A/C. But then, I've never had A/C,
central or otherwise, in anything but cars. By choosing not to live in
Alabamistan I've avoided a number of things. 300% humidity, chiggers,...


It was 90°F today and late this afternoon I was rolling around the complex to get my exercise. I rolled outside for a few minutes to see if I could slice the humid air with my hand. When I opened the door, I heard the call of summer, the cicadas were going wide open announcing to the world that they were horny.
ヽ(ヅ)ノ

[8~{} Uncle Bug Monster

Central AC quit
 

On 07/01/2017 08:49 PM, Uncle Monster wrote:
It was 90°F today and late this afternoon I was rolling around the complex to get my exercise. I rolled outside for a few minutes to see if I could slice the humid air with my hand. When I opened the door, I heard the call of summer, the cicadas were going wide open announcing to the world that they were horny.

I forgot that part of the Deep South -- the cacophony at night and I
don't mean mating red necks.

One thing I do miss about the east is lightning bugs. Supposedly there
are a few very small, isolated populations in this state hanging around
hot springs where there is a warm, humid microclimate but I've never
seen them.

Central AC quit
 

"Detective?" - "Defective" is more like it. I'll bet you couldn't detect
your way out of a used refrigerator carton even if both ends were open.

S

"Detective Marcus Bell" wrote in message
...
On 07/01/2017 07:08 AM, Sherlock.Homes wrote:
Seems to be 120vac from red to ground and 120vac from black to ground
but no
voltage between red and black, which should be 240vac. Reading was
taken at
the external dissconnect. What might cause this?

Thanks,
S


If red is L1 and black is L2, it seems like you don't know how to use a
volt meter properly.

Central AC quit
 

"Ralph Mowery" wrote in message
k.net...
In article ,
says...

On 07/01/2017 07:08 AM, Sherlock.Homes wrote:
Seems to be 120vac from red to ground and 120vac from black to ground
but no
voltage between red and black, which should be 240vac. Reading was
taken at
the external dissconnect. What might cause this?

Thanks,
S


If red is L1 and black is L2, it seems like you don't know how to use a
volt meter properly.

If the disconnect is not thrown , UM could be right, something is
letting the voltage through to the other side.

I did a lot of reading on this and UM is right - it's called backfed voltage
and it's a problem peculiar to 240V wiring. It could easilt account for the
problem since the circuit label shows a crankcase heater.

If the disconnect is thrown, then one side is the real voltage, and the
other side is probably the 'phantom' voltage caused by the high
impedance of the meter picking up the induced voltage on the wiring.

One side could be open somewhere.To find out which, take a light bulb,
anywhere from a couple of watts up to 100 watts and put across the line
from L1 to neutral and then L2 to neutral. Do that on the 'hot' side of
the disconnect.

Could be the breaker is bad, needs to be reset, or if fuses are used,
one bad fuse.

Checked the fuses, checked the breaker but couldn't find anything wrong.
Wife is insisting I call the pros. Will let you know what they find.

S

Central AC quit
 

wrote in message
...
On Sat, 1 Jul 2017 07:38:41 -0400, Detective Marcus Bell
wrote:

On 07/01/2017 07:08 AM, Sherlock.Homes wrote:
Seems to be 120vac from red to ground and 120vac from black to ground
but no
voltage between red and black, which should be 240vac. Reading was
taken at
the external dissconnect. What might cause this?

Thanks,
S


If red is L1 and black is L2, it seems like you don't know how to use a
volt meter properly.
Sounds to me like someone moved the 2 pole breaker and it's not on
both sides of the line. Both black and red are on the same side of the
service.

Nope. It failed without any manipulation.

S

Central AC quit
 

"Uncle Monster" wrote in message
...
On Saturday, July 1, 2017 at 6:09:00 AM UTC-5, Sherlock.Homes wrote:
Seems to be 120vac from red to ground and 120vac from black to ground but
no
voltage between red and black, which should be 240vac. Reading was taken
at
the external dissconnect. What might cause this?

Thanks,
S


One leg is dead and you're reading voltage through the crankcase heater.
make sure the disconnect is off before checking the voltage. Read the
voltages at the circuit breaker feeding the external disconnect. One side
could be tripped or there is a bad connection. Turn the breaker off
forcefully to make sure it clicks and resets if it tripped before.
Sometimes, a 2 pole breaker will trip and if you don't use enough force when
you turn it off, one side may not reset. I've seen it happen more than
once. ?(?)?

[8~{} Uncle Broken Monster

You're clearly the HVAC pro here. I will double check the 2 pole breaker.
That could explain a lot. Thanks!!!

S

Central AC quit
 

"trader_4" wrote in message
...
On Saturday, July 1, 2017 at 7:09:00 AM UTC-4, Sherlock.Homes wrote:
Seems to be 120vac from red to ground and 120vac from black to ground
but no
voltage between red and black, which should be 240vac. Reading was
taken at
the external dissconnect. What might cause this?

Thanks,
S

Is the disconnect open or closed?

Open and closed, with fuses and without and the fuses read about 1 ohm so I
think they are good. It's all moot now since the A/C guys are coming - my
window of opportunity passed - the wife wants the AC back YESTERDAY.

S

Central AC quit
 

On Sat, 1 Jul 2017 07:08:38 -0400, "Sherlock.Homes"
wrote:

Seems to be 120vac from red to ground and 120vac from black to ground but no
voltage between red and black, which should be 240vac. Reading was taken at
the external dissconnect. What might cause this?

Thanks,
S


Does this disconnect have fuses? Test the fuses individualy. They
burn out starting near the center.

Central AC quit
 

On 7/2/17 11:39 AM, Oren wrote:
On Sat, 1 Jul 2017 07:08:38 -0400, "Sherlock.Homes"
wrote:

Seems to be 120vac from red to ground and 120vac from black to ground but no
voltage between red and black, which should be 240vac. Reading was taken at
the external dissconnect. What might cause this?

Thanks,
S


Does this disconnect have fuses? Test the fuses individualy. They
burn out starting near the center.

One trick to test fuses is to check voltage from one end of the
fuse to the other.
It would be the same method as a continuity test. So I've been told
anyhow. Have you ever tried the end to end voltage test?

Central AC quit
 

On Sunday, July 2, 2017 at 3:04:18 PM UTC-4, Dean Hoffman wrote:
On 7/2/17 11:39 AM, Oren wrote:
On Sat, 1 Jul 2017 07:08:38 -0400, "Sherlock.Homes"
wrote:

Seems to be 120vac from red to ground and 120vac from black to ground but no
voltage between red and black, which should be 240vac. Reading was taken at
the external dissconnect. What might cause this?

Thanks,
S


Does this disconnect have fuses? Test the fuses individualy. They
burn out starting near the center.

One trick to test fuses is to check voltage from one end of the
fuse to the other.
It would be the same method as a continuity test. So I've been told
anyhow. Have you ever tried the end to end voltage test?

That works if the fuse is in a complete circuit, you'd get 0 V
if the fuse is good, full line voltage if it's open. But if
it's not a complete circuit, then you'd get zero either way.

Central AC quit
 

On 7/2/17 3:16 PM, trader_4 wrote:
On Sunday, July 2, 2017 at 3:04:18 PM UTC-4, Dean Hoffman wrote:

One trick to test fuses is to check voltage from one end of the
fuse to the other.
It would be the same method as a continuity test. So I've been told
anyhow. Have you ever tried the end to end voltage test?

That works if the fuse is in a complete circuit, you'd get 0 V
if the fuse is good, full line voltage if it's open. But if
it's not a complete circuit, then you'd get zero either way.

That trick might be a bit more useful checking points in relays or
contactors. I've always checked fuses by ohms or line to ground or
line to
line voltage.

Central AC quit
 

On Sun, 2 Jul 2017 14:04:11 -0500, Dean Hoffman
wrote:

On 7/2/17 11:39 AM, Oren wrote:
On Sat, 1 Jul 2017 07:08:38 -0400, "Sherlock.Homes"
wrote:

Seems to be 120vac from red to ground and 120vac from black to ground but no
voltage between red and black, which should be 240vac. Reading was taken at
the external dissconnect. What might cause this?

Thanks,
S


Does this disconnect have fuses? Test the fuses individualy. They
burn out starting near the center.

One trick to test fuses is to check voltage from one end of the
fuse to the other.
It would be the same method as a continuity test. So I've been told
anyhow. Have you ever tried the end to end voltage test?
Won't work if there is an open circuit either before or after the
fuse ----

Central AC quit
 

"Oren" wrote in message
...
On Sat, 1 Jul 2017 07:08:38 -0400, "Sherlock.Homes"
wrote:

Seems to be 120vac from red to ground and 120vac from black to ground but
no
voltage between red and black, which should be 240vac. Reading was taken
at
the external dissconnect. What might cause this?

Thanks,
S


Does this disconnect have fuses? Test the fuses individualy. They
burn out starting near the center.

Did that, About 1 ohm for the both of them. I think there's an intermittent
open in the cable in the conduit from the breaker panel to the outside
disconnect. Decided that it needed a recharge anyway so I'm calling the
HVAC folks tomorrow.

S

Central AC quit
 

Thanks to (almost) everyone who replied - it's in the hands of the HVAC guy
now. SWMBO wants cold. And as Dirty Harry once said "A man's got to know
his limitations."

S

"Dean Hoffman" wrote in message
...
On 7/2/17 3:16 PM, trader_4 wrote:
On Sunday, July 2, 2017 at 3:04:18 PM UTC-4, Dean Hoffman wrote:

One trick to test fuses is to check voltage from one end of the
fuse to the other.
It would be the same method as a continuity test. So I've been told
anyhow. Have you ever tried the end to end voltage test?

That works if the fuse is in a complete circuit, you'd get 0 V
if the fuse is good, full line voltage if it's open. But if
it's not a complete circuit, then you'd get zero either way.

That trick might be a bit more useful checking points in relays
or
contactors. I've always checked fuses by ohms or line to ground or
line to
line voltage.

Central AC quit
 

On Sunday, July 2, 2017 at 11:25:35 PM UTC-4, Sherlock.Homes wrote:
disconnect. Decided that it needed a recharge anyway so I'm calling the
HVAC folks tomorrow.

S

refrigerant does not get used up.

If it needs a recharge, it has a leak. Fix the leak.

(or it wasn't charged properly in the first place. But the leak is likely.)

Central AC quit
 

In article ,
says...

On Sunday, July 2, 2017 at 3:04:18 PM UTC-4, Dean Hoffman wrote:
On 7/2/17 11:39 AM, Oren wrote:


Does this disconnect have fuses? Test the fuses individualy. They
burn out starting near the center.

One trick to test fuses is to check voltage from one end of the
fuse to the other.
It would be the same method as a continuity test. So I've been told
anyhow. Have you ever tried the end to end voltage test?

That works if the fuse is in a complete circuit, you'd get 0 V
if the fuse is good, full line voltage if it's open. But if
it's not a complete circuit, then you'd get zero either way.

While somewhat expensive at about $ 100 for a casual home user, I like
the Fluke T-5 tester. Just set it for ohms and put it across the fuse.
If it shows low ohms, the fuse is probably good, if it gives you an
overload indication, the fuse is probably bad. The meter is almost blow
up proof so that test works fine. I and several others where I worked
do it all the time on circuits up to 480 volts and never had a tester to
fail.

For the simple meters or even the neon bulb type testers, go from each
side of the fuse to the neutral wire. If it shows power on both sides,
then go across the fuse and if it shows power, the fuse is bad. If any
doubt, just pull the fuse and check it with an ohm meter. Should be
very close to zero ohms.

Central AC quit
 

On Mon, 3 Jul 2017 08:26:01 -0400, "Sherlock.Homes"
wrote:

Thanks to (almost) everyone who replied - it's in the hands of the HVAC guy
now. SWMBO wants cold. And as Dirty Harry once said "A man's got to know
his limitations."

I would not be surprised if one or more bad capacitors are found.

Central AC quit
 

rbowman posted for all of us...



On 07/01/2017 08:49 PM, Uncle Monster wrote:
It was 90°F today and late this afternoon I was rolling around the complex to get my exercise. I rolled outside for a few minutes to see if I could slice the humid air with my hand. When I opened the door, I heard the call of summer, the cicadas were going wide open announcing to the world that they were horny.

I forgot that part of the Deep South -- the cacophony at night and I
don't mean mating red necks.

One thing I do miss about the east is lightning bugs. Supposedly there
are a few very small, isolated populations in this state hanging around
hot springs where there is a warm, humid microclimate but I've never
seen them.

Lightning bugs seem to be in short supply this year. Haven't heard why.

--
Tekkie

Sherlock Holmes, father of John Holmes, talks about "Central ACwent out and gawddamit all!"
 

On 7/2/2017 10:34 AM, Snohomo Jackie G wrote:
He is getting old and out of date. Be nice to this old coot.

Yer 78 and the only pussy you've ever
got is from yer cat..little Jackie.

LoLoLoL

Central AC quit
 

"Stormin' Norman" wrote in message
...
On Mon, 3 Jul 2017 08:26:01 -0400, "Sherlock.Homes"
wrote:

Thanks to (almost) everyone who replied - it's in the hands of the HVAC
guy
now. SWMBO wants cold. And as Dirty Harry once said "A man's got to
know
his limitations."

I would not be surprised if one or more bad capacitors are found.

Nor I but I don't have a way to test them easily whereas an HVAC guy with a
truck probably has spares he can just swap test. Probably can meter it,
too. I figure it's always worth looking at stuff like this in case it's
something easy. It never hurts to learn the terminology. Three days ago I
didn't know about backfeeding and crankcase heaters on A/C's so it wasn't a
total loss mucking around but I suspect I will be charged the "you tried
doing it yourself first" fee. I'll just say "I took it apart to help you -
you owe me an pre-diagnosis assistance discount!" (-:

S