Fan Sticks On


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Old 01-02-08, 03:44 PM
D
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Fan Sticks On

I have an old, rectangular, analog Honeywell thermostat (6-wire). I know the number of wires because I was doing some research on replacing the thermostat. I understand heat pump systems can be a little touchy as far as switching to a digital thermostat (touchy for DIY for a moron like myself that is).
Anyways, here's the main problem:
I've had problems with the fan (possibly heat - I can't tell b/c heat pumps suck in general) getting stuck on.
There are three controls:
- temperature dial
- fan (AUTO or ON)
- EM. HEAT, HEAT, OFF, or COOL
So before I left for two weeks vacation, I went to turn my heat off. I turned temp all the way down, fan on AUTO, and the other switch to OFF. Fan stayed on. Jiggled btw the OFF and COOL settings, fan stayed on. Finally I just left thinking it would kick off eventually. I returned two weeks later with the fan running (and a 65 deg apt w/ outside air 30 deg). I jiggled the switch again and finally got the fan to turn off. After two weeks of heat running with me not here, I'm ready to do something about it. My electric bill will hurt. I was guessing it was a thermostat problem. PROs PLEASE HELP ME!
DT
 
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Old 01-02-08, 05:08 PM
pflor's Avatar
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d:
I know this is no funny matter to you, less so when you get your bill; but you have such a way of telling your story that I could not stop laughing.

Please let us know the T-stat Mfr & M/N...and if possible...the wallplate M/N too (the wallplate is that component where the thermostat wires are connected).

And if it is not too much to ask, to help you with the correct thermostat replacement, how about the outdoor unit Mfr. & M/N info.
 
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Old 01-02-08, 05:59 PM
D
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pflor -

firslty, thank you, you're a god send.
secondly - so you think it's the T-stat malfunctioning?

T-stat:
Honeywell
T874R1137
HQ711597HW

Wallplate:
Q674L1132
711598

Outdoor Unit Heat Pump:
High Efficiency 5000
Model No. CH5524UKA2
MFR No. NCH5524UKA2
 
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Old 01-02-08, 07:18 PM
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I do think is the t-stat, but will look at the honeywell literature and will get back to you tomorrow in the AM

The kids upstairs won't go to sleep unless I go up & crack the whip.
 
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Old 01-03-08, 09:18 AM
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Hi D...
Since you know about your t-stat having 6 wires hooked up to it (to the subbase really), I take it that you were able to remove the thermostat [T874R1137]
[img=http://img2.freeimagehosting.net/uploads/61f54ed4b3.jpg]
With the thermostat off, screwed on the wall is the subbase Q674L1132
[img=http://img2.freeimagehosting.net/uploads/675718d9b4.jpg]
The "6" wires you mention should be connected (one each) to the following terminals: G, R, E, B (or maybe "O" but not both), X, and Y.

Next time this problem happens, turn the system switch to OFF [the one with EM.HT, HEAT, OFF, COOL] and the fan switch to AUTO (not ON) and proceed to remove the thermostat. Everything should stop dead on its tracks...If so, the thermostat is bad. If the fan stays ON, you'll now test for possibly a defective subbase (don't put back the t-stat) - with a screwdriver disconnect the "G" terminal...this should stop the fan...If the fan went OFF, you have a bad subbase.
If with the G terminal disconnected the fan still stays ON, we have a different problem, likely defective contacts in the fan-relay.

Honeywell recommends the TH5220D as a replacement.
[img=http://img2.freeimagehosting.net/uploads/7b5694ecfa.jpg]

Your description of the outdoor unit does not help me. Who's the manufacturer? How about a picture?

Hope this helps.
 
 

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