I'm having some odd fan cycling problem on my Carrier furnace. It has
behaved oddly ever since it was installed. At the furnace controller
card no yellow wire is attached. The voltage on the Green wire is
varying and when it gets down to 18VAC the blower fan kicks off. The
red wire is a solid 27VAC.

I'm still using an old round Honeywell thermostat and I'm guessing the
mercury switch in the thermostat has gone bad. Is that a good guess?
When I get a new thermostat should I add a yellow wire?

Also, is the wiring diagram below essentially accurate as a typical
example?

http://xtronics.com/reference/thermostat_wires.html

Thanks!

To the best of my knowledge, Honeywell has sold over 27 billion yo-yo
thermostats since their inception, and none have ever gone bad. Should you
add a yellow wire? Why, what for and what would you connect it to?
Thermostat cables come with a variety of colors, so don't necessarily expect
colors to have definitive meanings. Your best bet is to contact a HVAC
professional and let him check it out



"Davej" wrote in message
ups.com...
I'm having some odd fan cycling problem on my Carrier furnace. It has
behaved oddly ever since it was installed. At the furnace controller
card no yellow wire is attached. The voltage on the Green wire is
varying and when it gets down to 18VAC the blower fan kicks off. The
red wire is a solid 27VAC.

I'm still using an old round Honeywell thermostat and I'm guessing the
mercury switch in the thermostat has gone bad. Is that a good guess?
When I get a new thermostat should I add a yellow wire?

Also, is the wiring diagram below essentially accurate as a typical
example?

http://xtronics.com/reference/thermostat_wires.html

Thanks!

RBM wrote:
To the best of my knowledge, Honeywell has sold over 27 billion yo-yo
thermostats since their inception, and none have ever gone bad.
Should you add a yellow wire? Why, what for and what would you
connect it to? Thermostat cables come with a variety of colors, so
don't necessarily expect colors to have definitive meanings. Your
best bet is to contact a HVAC professional and let him check it out



"Davej" wrote in message
ups.com...
I'm having some odd fan cycling problem on my Carrier furnace. It has
behaved oddly ever since it was installed. At the furnace controller
card no yellow wire is attached. The voltage on the Green wire is
varying and when it gets down to 18VAC the blower fan kicks off. The
red wire is a solid 27VAC.

I'm still using an old round Honeywell thermostat and I'm guessing
the mercury switch in the thermostat has gone bad. Is that a good
guess? When I get a new thermostat should I add a yellow wire?

Also, is the wiring diagram below essentially accurate as a typical
example?

http://xtronics.com/reference/thermostat_wires.html

Thanks!

You right about having the system checked out by his service company.

In the business you try to stay with the same code which I learned over 20
years ago:

RED = Power= Hot (24volt)
GREEN=Go=Blower
WHITE=Snow=Heat
YELLOW=Sun=Air Conditioning
or
BLUE=Cool=Air Conditioning

--
Moe Jones
HVAC Service Technician
Energy Equalizers Inc.
Houston, Texas
www.EnergyEqualizers.com

That's a qute rhyme Moe Jo....

Zyp

"Moe Jones" wrote in message
...
RBM wrote:
To the best of my knowledge, Honeywell has sold over 27 billion yo-yo
thermostats since their inception, and none have ever gone bad.
Should you add a yellow wire? Why, what for and what would you
connect it to? Thermostat cables come with a variety of colors, so
don't necessarily expect colors to have definitive meanings. Your
best bet is to contact a HVAC professional and let him check it out



"Davej" wrote in message
ups.com...
I'm having some odd fan cycling problem on my Carrier furnace. It has
behaved oddly ever since it was installed. At the furnace controller
card no yellow wire is attached. The voltage on the Green wire is
varying and when it gets down to 18VAC the blower fan kicks off. The
red wire is a solid 27VAC.

I'm still using an old round Honeywell thermostat and I'm guessing
the mercury switch in the thermostat has gone bad. Is that a good
guess? When I get a new thermostat should I add a yellow wire?

Also, is the wiring diagram below essentially accurate as a typical
example?

http://xtronics.com/reference/thermostat_wires.html

Thanks!

You right about having the system checked out by his service company.

In the business you try to stay with the same code which I learned over 20
years ago:

RED = Power= Hot (24volt)
GREEN=Go=Blower
WHITE=Snow=Heat
YELLOW=Sun=Air Conditioning
or
BLUE=Cool=Air Conditioning

--
Moe Jones
HVAC Service Technician
Energy Equalizers Inc.
Houston, Texas
www.EnergyEqualizers.com

Those old round thermostats are only for heat, with 2 contacts (R & W), no?

You need a FAN ON switch on the thermostat to activate the green.

The furnace fan will turn itself on when heating, but not when cooling.

-Pat

Davej wrote:
I'm having some odd fan cycling problem on my Carrier furnace. It has
behaved oddly ever since it was installed. At the furnace controller
card no yellow wire is attached. The voltage on the Green wire is
varying and when it gets down to 18VAC the blower fan kicks off. The
red wire is a solid 27VAC.

I'm still using an old round Honeywell thermostat and I'm guessing the
mercury switch in the thermostat has gone bad. Is that a good guess?
When I get a new thermostat should I add a yellow wire?

Also, is the wiring diagram below essentially accurate as a typical
example?

http://xtronics.com/reference/thermostat_wires.html

Thanks!

Davej wrote:
I'm having some odd fan cycling problem on my Carrier furnace. It has
behaved oddly ever since it was installed. At the furnace controller
card no yellow wire is attached. The voltage on the Green wire is
varying and when it gets down to 18VAC the blower fan kicks off. The
red wire is a solid 27VAC.

I'm still using an old round Honeywell thermostat and I'm guessing the
mercury switch in the thermostat has gone bad. Is that a good guess?
When I get a new thermostat should I add a yellow wire?

Also, is the wiring diagram below essentially accurate as a typical
example?

http://xtronics.com/reference/thermostat_wires.html

Thanks!

Hi,
That 18V is a problem. Spec calls for minimum 20V. You have bad poor
connection somewhere or thermostat wet contaq ct is resistive.

They make a heat-cool sub base for it to accommodate a variety of
applications



"Pat Coghlan" wrote in message
...
Those old round thermostats are only for heat, with 2 contacts (R & W),
no?

You need a FAN ON switch on the thermostat to activate the green.

The furnace fan will turn itself on when heating, but not when cooling.

-Pat

Davej wrote:
I'm having some odd fan cycling problem on my Carrier furnace. It has
behaved oddly ever since it was installed. At the furnace controller
card no yellow wire is attached. The voltage on the Green wire is
varying and when it gets down to 18VAC the blower fan kicks off. The
red wire is a solid 27VAC.

I'm still using an old round Honeywell thermostat and I'm guessing the
mercury switch in the thermostat has gone bad. Is that a good guess?
When I get a new thermostat should I add a yellow wire?

Also, is the wiring diagram below essentially accurate as a typical
example?

http://xtronics.com/reference/thermostat_wires.html

Thanks!

On Aug 8, 8:57 pm, "RBM" rbm2(remove wrote:
"Pat Coghlan" wrote:
Davej wrote:

I'm having some odd fan cycling problem on my Carrier furnace. It has
behaved oddly ever since it was installed. At the furnace controller
card no yellow wire is attached. The voltage on the Green wire is
varying and when it gets down to 18VAC the blower fan kicks off. The
red wire is a solid 27VAC.

I'm still using an old round Honeywell thermostat and I'm guessing the
mercury switch in the thermostat has gone bad. Is that a good guess?
When I get a new thermostat should I add a yellow wire?

Also, is the wiring diagram below essentially accurate as a typical
example?

http://xtronics.com/reference/thermostat_wires.html

Those old round thermostats are only for heat, with 2 contacts (R & W),
no?

You need a FAN ON switch on the thermostat to activate the green.

The furnace fan will turn itself on when heating, but not when cooling.

They make a heat-cool sub base for it to accommodate a variety of
applications


I think my problem may be that the switch contacts in the base plate
have gone bad. I cleaned them with alcohol but they may have lost
their plating. Also I did find appropriate schematic info on the
Honeywell website (CT87B thermostat looks like it). Thanks for the
replies.

On Wed, 08 Aug 2007 19:59:48 -0400, Pat Coghlan
wrote:

Those old round thermostats are only for heat, with 2 contacts (R & W), no?

My house came with AC and a round Honeywell thermostat. I only
changed it because I wanted an automatic setback for work and
sleeping.

You need a FAN ON switch on the thermostat to activate the green.

It has a switch like that too. It's in a box in the basement, and I
may connect it to the burglar alarm so that if the furnace goes out
while I'm out of town, the monitoring company will know.

snip

-Pat

Davej wrote:
I'm having some odd fan cycling problem on my Carrier furnace. It has
behaved oddly ever since it was installed. At the furnace controller
card no yellow wire is attached. The voltage on the Green wire is
varying and when it gets down to 18VAC the blower fan kicks off. The
red wire is a solid 27VAC.

I'm still using an old round Honeywell thermostat and I'm guessing the
mercury switch in the thermostat has gone bad. Is that a good guess?
When I get a new thermostat should I add a yellow wire?

Also, is the wiring diagram below essentially accurate as a typical
example?

http://xtronics.com/reference/thermostat_wires.html

Thanks!

On Thu, 09 Aug 2007 07:14:01 -0700, Davej wrote:

On Aug 8, 8:57 pm, "RBM" rbm2(remove wrote:
"Pat Coghlan" wrote:
Davej wrote:

I'm having some odd fan cycling problem on my Carrier furnace. It has
behaved oddly ever since it was installed. At the furnace controller
card no yellow wire is attached. The voltage on the Green wire is
varying and when it gets down to 18VAC the blower fan kicks off. The
red wire is a solid 27VAC.

I'm still using an old round Honeywell thermostat and I'm guessing the
mercury switch in the thermostat has gone bad. Is that a good guess?
When I get a new thermostat should I add a yellow wire?

Also, is the wiring diagram below essentially accurate as a typical
example?

http://xtronics.com/reference/thermostat_wires.html

Those old round thermostats are only for heat, with 2 contacts (R & W),
no?

You need a FAN ON switch on the thermostat to activate the green.

The furnace fan will turn itself on when heating, but not when cooling.

They make a heat-cool sub base for it to accommodate a variety of
applications


I think my problem may be that the switch contacts in the base plate
have gone bad. I cleaned them with alcohol but they may have lost
their plating. Also I did find appropriate schematic info on the
Honeywell website (CT87B thermostat looks like it). Thanks for the
replies.

If you think the switch contacts may be bad, bypass them. No need to
buy a test replacement thermostat. Either bypass the switch with a
separate wire**, or disconnect the wires and touch them together***.

**Everyone should have 10 or even 20 jumper wires with alligator clips
on the end. You can make special ones, like 6 feet long, and you can
buy them in bags of 10 of 5 different colors from radio shack. You
may be able to clip the alligator clips to the screws on the back of
the thermostat, or to the wires.

***It's only 24 volts and you won't even feel it. Or you can probably
use even a single alligator clip, paper clip, wire nut, or twist them
together a little bit. It's only for testing.

Or disconnect one wire and mount it under the screw that goes to the
other wire.

P&M, reply by post.

On Thu, 09 Aug 2007 01:09:29 GMT, Tony Hwang wrote:

Davej wrote:
I'm having some odd fan cycling problem on my Carrier furnace. It has
behaved oddly ever since it was installed. At the furnace controller
card no yellow wire is attached. The voltage on the Green wire is
varying and when it gets down to 18VAC the blower fan kicks off. The
red wire is a solid 27VAC.

I'm still using an old round Honeywell thermostat and I'm guessing the
mercury switch in the thermostat has gone bad. Is that a good guess?
When I get a new thermostat should I add a yellow wire?

Also, is the wiring diagram below essentially accurate as a typical
example?

http://xtronics.com/reference/thermostat_wires.html

Thanks!

Hi,
That 18V is a problem. Spec calls for minimum 20V. You have bad poor
connection somewhere or thermostat wet contaq ct is resistive.

You're right. Except, Is it possible for a mercury switch to be
resistive?

Could his 24 volt transformer be failing? Maybe not since he has 27
volts most of the time. But I like this story, so I'll tell it again
anyhow. I moved into this house in late May, and had 4 ffriends
from NYC for July 4 weekend. At noon on Saturday, the AC failed. At
6PM the water failed. And at 6PM Sunday, the electricity failed.
And the house was almost new!

But we had a good time, and after they left, I checked the oil furnace
and the 24 volt transformer that powered the AC control system also
had failed to zero. They wanted 150 for a whole control unit, but
sold me a transformer for 20. Too big for the space so I mounted it a
foot away. STill working fine 24 years later.

On Aug 9, 1:46 pm, mm wrote:
On Thu, 09 Aug 2007 07:14:01 -0700, Davej wrote:
On Aug 8, 8:57 pm, "RBM" rbm2(remove wrote:
"Pat Coghlan" wrote:
Davej wrote:

I'm having some odd fan cycling problem on my Carrier furnace. It has
behaved oddly ever since it was installed. At the furnace controller
card no yellow wire is attached. The voltage on the Green wire is
varying and when it gets down to 18VAC the blower fan kicks off. The
red wire is a solid 27VAC.

I'm still using an old round Honeywell thermostat and I'm guessing the
mercury switch in the thermostat has gone bad. Is that a good guess?
When I get a new thermostat should I add a yellow wire?

Also, is the wiring diagram below essentially accurate as a typical
example?

http://xtronics.com/reference/thermostat_wires.html

Those old round thermostats are only for heat, with 2 contacts (R & W),
no?

You need a FAN ON switch on the thermostat to activate the green.

The furnace fan will turn itself on when heating, but not when cooling.

They make a heat-cool sub base for it to accommodate a variety of
applications

I think my problem may be that the switch contacts in the base plate
have gone bad. I cleaned them with alcohol but they may have lost
their plating. Also I did find appropriate schematic info on the
Honeywell website (CT87B thermostat looks like it). Thanks for the
replies.

If you think the switch contacts may be bad, bypass them. No need to
buy a test replacement thermostat. Either bypass the switch with a
separate wire**, or disconnect the wires and touch them together***.

**Everyone should have 10 or even 20 jumper wires with alligator clips
on the end. You can make special ones, like 6 feet long, and you can
buy them in bags of 10 of 5 different colors from radio shack. You
may be able to clip the alligator clips to the screws on the back of
the thermostat, or to the wires.

***It's only 24 volts and you won't even feel it. Or you can probably
use even a single alligator clip, paper clip, wire nut, or twist them
together a little bit. It's only for testing.

Or disconnect one wire and mount it under the screw that goes to the
other wire.

Yes I've tried jumpering, and once I found the thermostat schematic
the situation became a lot less mysterious. I'm going to try the green
wire attached to the (O)range thermostat terminal -- and let the
blower fan run when I have the AC on.

http://yourhome.honeywell.com/Consum...nd/Default.htm

I've got no experience with heat pumps. But the furnace and
central air diagram is not wired the way I would have drawn the
diagram.

--

Christopher A. Young
You can't shout down a troll.
You have to starve them.
..

"Davej" wrote in message
ups.com...
:
: Also, is the wiring diagram below essentially accurate as a
typical
: example?
:
: http://xtronics.com/reference/thermostat_wires.html
:
: Thanks!
:

This is what I believe it should show...

http://home.att.net/~galt_57/thermostat.bmp

On Aug 10, "Stormin Mormon"
wrote:
I've got no experience with heat pumps. But the furnace and
central air diagram is not wired the way I would have drawn the
diagram.

--

Christopher A. Young
You can't shout down a troll.
You have to starve them.
.

"Davej" wrote:
:
:
: Also, is the wiring diagram below essentially accurate as a
typical
: example?
:
:http://xtronics.com/reference/thermostat_wires.html
:
: Thanks!
:

That is very definitely not how I've ever seen a stat wired. If
you wired a unit like that, it would not work very well for
cooling. Actually, it would not cool the house at all.

--

Christopher A. Young
You can't shout down a troll.
You have to starve them.
..

"Davej" wrote in message
ups.com...
: This is what I believe it should show...
:
: http://home.att.net/~galt_57/thermostat.bmp
:

Ok Stormy;

His diagram actually is sound. The only problem I see is that with the
[newer] computer boards on some furnaces require that the "Y" terminal be
connected to the furance computer board as well. Some newer furnace boards
run the "continuously fan" at a slower speed than with the air conditioning
["G" terminal]. The computer recgonizes the demand for air conditioning
["Y" terminal] and runs the blower at highest speed.

Stormy, go back and check the wiring again. You will see it is correct.
2-wire condenser - 4 wire thermostat.

Zyp


"Stormin Mormon" wrote in message
...
That is very definitely not how I've ever seen a stat wired. If
you wired a unit like that, it would not work very well for
cooling. Actually, it would not cool the house at all.

--

Christopher A. Young
You can't shout down a troll.
You have to starve them.
.

"Davej" wrote in message
ups.com...
: This is what I believe it should show...
:
: http://home.att.net/~galt_57/thermostat.bmp
:

Other than the Y signal to the furnace, the rest of it looked OK.
The lower fan speed won't do as good a job of pushing cold air up
hill. Would work fine if the air handler was in the attic. Where
I am, furnaces are typically in cellars.

--

Christopher A. Young
You can't shout down a troll.
You have to starve them.
..

"Zephyr" wrote in message
news : Ok Stormy;
:
: His diagram actually is sound. The only problem I see is that
with the
: [newer] computer boards on some furnaces require that the "Y"
terminal be
: connected to the furance computer board as well. Some newer
furnace boards
: run the "continuously fan" at a slower speed than with the air
conditioning
: ["G" terminal]. The computer recgonizes the demand for air
conditioning
: ["Y" terminal] and runs the blower at highest speed.
:
: Stormy, go back and check the wiring again. You will see it is
correct.
: 2-wire condenser - 4 wire thermostat.
:
: Zyp
:
: :
: : http://home.att.net/~galt_57/thermostat.bmp
: :
:
:
:
:

Up hill????

The reason for the "higher" air speed is that cool air is dense [heaver]
than heated air. Take a look at a pscyometric chart and plot... you'll see
the cooled air carries more weight per foot than heated air, thus needs more
torque.

Actually, you can run air conditioning down to 200 cfm per ton Stormy, but
the results are dismal. You will remove a considerable amount of moisture
from the air but will pay for it in performance. 25 years ago, 325 cfm per
ton was the norm and 400 cfm per ton on heat pumps. Now the norm is 400 cfm
per ton on air conditioning and 450 cfm per ton on heat pumps. Why the
difference? Performance.

Zyp

"Stormin Mormon" wrote in message
...
Other than the Y signal to the furnace, the rest of it looked OK.
The lower fan speed won't do as good a job of pushing cold air up
hill. Would work fine if the air handler was in the attic. Where
I am, furnaces are typically in cellars.

--

Christopher A. Young
You can't shout down a troll.
You have to starve them.
.

"Zephyr" wrote in message
news : Ok Stormy;
:
: His diagram actually is sound. The only problem I see is that
with the
: [newer] computer boards on some furnaces require that the "Y"
terminal be
: connected to the furance computer board as well. Some newer
furnace boards
: run the "continuously fan" at a slower speed than with the air
conditioning
: ["G" terminal]. The computer recgonizes the demand for air
conditioning
: ["Y" terminal] and runs the blower at highest speed.
:
: Stormy, go back and check the wiring again. You will see it is
correct.
: 2-wire condenser - 4 wire thermostat.
:
: Zyp
:
: :
: : http://home.att.net/~galt_57/thermostat.bmp
: :
:
:
:
:

mm wrote:
On Thu, 09 Aug 2007 01:09:29 GMT, Tony Hwang wrote:


Davej wrote:

I'm having some odd fan cycling problem on my Carrier furnace. It has
behaved oddly ever since it was installed. At the furnace controller
card no yellow wire is attached. The voltage on the Green wire is
varying and when it gets down to 18VAC the blower fan kicks off. The
red wire is a solid 27VAC.

I'm still using an old round Honeywell thermostat and I'm guessing the
mercury switch in the thermostat has gone bad. Is that a good guess?
When I get a new thermostat should I add a yellow wire?

Also, is the wiring diagram below essentially accurate as a typical
example?

http://xtronics.com/reference/thermostat_wires.html

Thanks!


Hi,
That 18V is a problem. Spec calls for minimum 20V. You have bad poor
connection somewhere or thermostat wet contaq ct is resistive.


You're right. Except, Is it possible for a mercury switch to be
resistive?

Could his 24 volt transformer be failing? Maybe not since he has 27
volts most of the time. But I like this story, so I'll tell it again
anyhow. I moved into this house in late May, and had 4 ffriends
from NYC for July 4 weekend. At noon on Saturday, the AC failed. At
6PM the water failed. And at 6PM Sunday, the electricity failed.
And the house was almost new!

But we had a good time, and after they left, I checked the oil furnace
and the 24 volt transformer that powered the AC control system also
had failed to zero. They wanted 150 for a whole control unit, but
sold me a transformer for 20. Too big for the space so I mounted it a
foot away. STill working fine 24 years later.
Hi,
How wet switch makes connection? Mercury bubble bridges two electrodes.
Those metal parts can get you know what. Easy thing to prove that is
measure across the switch with meter tilting the bulb back and forth.

Yep, so much easier to use attic air handlers for AC, and blow
the heavier cold air down hill.

Thanks for the stats on CFM, makes a lot of sense.

--

Christopher A. Young
You can't shout down a troll.
You have to starve them.
..

"Zephyr" wrote in message
news:stCdnZcjDLSlGSPbnZ2dnUVZ_qKgnZ2d@championbroa dband.com...
: Up hill????
:
: The reason for the "higher" air speed is that cool air is dense
[heaver]
: than heated air. Take a look at a pscyometric chart and
plot... you'll see
: the cooled air carries more weight per foot than heated air,
thus needs more
: torque.
:
: Actually, you can run air conditioning down to 200 cfm per ton
Stormy, but
: the results are dismal. You will remove a considerable amount
of moisture
: from the air but will pay for it in performance. 25 years ago,
325 cfm per
: ton was the norm and 400 cfm per ton on heat pumps. Now the
norm is 400 cfm
: per ton on air conditioning and 450 cfm per ton on heat pumps.
Why the
: difference? Performance.
:
: Zyp
:
: "Stormin Mormon" wrote in
message
: ...
: Other than the Y signal to the furnace, the rest of it looked
OK.
: The lower fan speed won't do as good a job of pushing cold
air up
: hill. Would work fine if the air handler was in the attic.
Where
: I am, furnaces are typically in cellars.
:
: --
:
: Christopher A. Young
: You can't shout down a troll.
: You have to starve them.
: .
:
: "Zephyr" wrote in message
:
news : : Ok Stormy;
: :
: : His diagram actually is sound. The only problem I see is
that
: with the
: : [newer] computer boards on some furnaces require that the
"Y"
: terminal be
: : connected to the furance computer board as well. Some
newer
: furnace boards
: : run the "continuously fan" at a slower speed than with the
air
: conditioning
: : ["G" terminal]. The computer recgonizes the demand for air
: conditioning
: : ["Y" terminal] and runs the blower at highest speed.
: :
: : Stormy, go back and check the wiring again. You will see
it is
: correct.
: : 2-wire condenser - 4 wire thermostat.
: :
: : Zyp
: :
: : :
: : : http://home.att.net/~galt_57/thermostat.bmp
: : :
: :
: :
: :
: :
:
:
:
:

On Aug 11, 11:04 pm, Tony Hwang wrote:
mm wrote:
On Thu, 09 Aug 2007 01:09:29 GMT, Tony Hwang wrote:

Davej wrote:

I'm having some odd fan cycling problem on my Carrier furnace. It has
behaved oddly ever since it was installed. At the furnace controller
card no yellow wire is attached. The voltage on the Green wire is
varying and when it gets down to 18VAC the blower fan kicks off. The
red wire is a solid 27VAC.

I'm still using an old round Honeywell thermostat and I'm guessing the
mercury switch in the thermostat has gone bad. Is that a good guess?
When I get a new thermostat should I add a yellow wire?

Also, is the wiring diagram below essentially accurate as a typical
example?

http://xtronics.com/reference/thermostat_wires.html

Thanks!

Hi,
That 18V is a problem. Spec calls for minimum 20V. You have bad poor
connection somewhere or thermostat wet contaq ct is resistive.

You're right. Except, Is it possible for a mercury switch to be
resistive?

Could his 24 volt transformer be failing? Maybe not since he has 27
volts most of the time. But I like this story, so I'll tell it again
anyhow. I moved into this house in late May, and had 4 ffriends
from NYC for July 4 weekend. At noon on Saturday, the AC failed. At
6PM the water failed. And at 6PM Sunday, the electricity failed.
And the house was almost new!

But we had a good time, and after they left, I checked the oil furnace
and the 24 volt transformer that powered the AC control system also
had failed to zero. They wanted 150 for a whole control unit, but
sold me a transformer for 20. Too big for the space so I mounted it a
foot away. STill working fine 24 years later.

Hi,
How wet switch makes connection? Mercury bubble bridges two electrodes.
Those metal parts can get you know what. Easy thing to prove that is
measure across the switch with meter tilting the bulb back and forth.


I suspected the mercury switch at first but the problem turned out to
be the mechanical ON/AUTO switch in the thermostat base.

I guess connecting the yellow wire to the furnace would increase the
blower speed but I think I prefer running the blower continuously at a
lower speed. I don't want the compressor and blower fan to turn off
simultaneously and I don't know if connecting the yellow wire would
activate a delay.