I purchased this t-stat last winter:
http://brigita.blogspot.com/img/Therm.jpg
It worked good for my heating system. But I recently turned on my CAC
for the first time and noticed a wierd problem.
The T-stat has a built in compressor protection feature. It waits 5
minutes before starting the compressor if the T-stat cycles too
quickly. Which is fine only theres one problem:
When I tested it out, the compressor came back on, but the blower motor
stopped working, as if the 2 had been reversed. I double checked the
T-Stat wiring and it is good. According to my Trane furnace schematic,
the compressor relay is hooked up to y and c terminals on the furnace
circuit board, which they are. A point to note, there is no C terminal
on this T-stat. The manual says " Do not connect the c wire, you will
not use it". Also there is an R and RC terminal on the T-stat jumped
together. The manual says to leave the jumper connected if all I have
is an R terminal on the furnace.
I plan to call Honeywell for support, but does anyone have any input
what might be wrong?

Mikepier wrote:

I purchased this t-stat last winter:
http://brigita.blogspot.com/img/Therm.jpg
It worked good for my heating system. But I recently turned on my CAC
for the first time and noticed a wierd problem.
The T-stat has a built in compressor protection feature. It waits 5
minutes before starting the compressor if the T-stat cycles too
quickly. Which is fine only theres one problem:
When I tested it out, the compressor came back on, but the blower motor
stopped working, as if the 2 had been reversed. I double checked the
T-Stat wiring and it is good. According to my Trane furnace schematic,
the compressor relay is hooked up to y and c terminals on the furnace
circuit board, which they are. A point to note, there is no C terminal
on this T-stat. The manual says " Do not connect the c wire, you will
not use it". Also there is an R and RC terminal on the T-stat jumped
together. The manual says to leave the jumper connected if all I have
is an R terminal on the furnace.
I plan to call Honeywell for support, but does anyone have any input
what might be wrong?

Maybe the high speed winding on your blower motor is faulty or
disconnected? Does the blower motor run if you set it to "on"
rather than "auto" at the thermostat?

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The fan switch functions normally. I believe that my fan motor is only
one speed. Although there are 4 leads coming out of it, I think its
configured for the highest speed.

UPDATE: Well, I don't know what happened. I tries it again this morning
and it seems to work. Both the blower and the compressor does not come
on now. I'll keep an eye on it. But I could have sworn that was not the
case yesterday.