emergency heat light on - http://www.hvacmechanic.com/ Forums
Original message
| blowout
 |  "emergency heat light on"
, posted Sat 19 Jun 12:09:  
I have an older Trane heat pump TWD742A100A1. The system will be functioning fine in the AC mode keeping the house cool and then the auxillary heat light comes on and I get heat from the vents. Turning the thermostat OFF and back on has no effect. I have found that cycling the power to the blower cures the problem. Turning off the power to the compressor does not. I suspect that turning the power off to the blower cycles the low voltage pressure. The red LED on the defrost control board flashes either 2 or 3 times. I suspect the control board is bad because the quick cycling of power would not allow timne for high pressure to disapate. Got any thoughts?
[this message was edited by blowout on Sat 19 Jun 12:22] |
| Replies:
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| Xenos
Webmaster 
| "Re(1):emergency heat light on" , posted Sat 19 Jun 17:04
For a test disconnect the W wire from the thermostat, this is aux heat. this way we may be able to narrow down the problem.
Xenos.
The best way to escape a problem is to solve it.
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| | blowout
| "Re(2):emergency heat light on" , posted Sat 19 Jun 19:13
With W disconnected, the aux heat light went off and the systemn did not blow hot air. ( I think I forgot to mention the compressor fan does not run when this happens, as soon as I cycle the air handler power it starts again and the aux heat light goes off)
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| | Xenos
Webmaster
| "Re(3):emergency heat light on" , posted Sat 19 Jun 19:23
If it's not hapening with the W off, it has something to do with the thermostat as W is the terminal the thermostat uses to control the heat.
Xenos.
The best way to escape a problem is to solve it.
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| | blowout
| "Re(4):emergency heat light on" , posted Mon 21 Jun 10:55
So far, the problem has not re-occured...however this is an intermittent problem that lately has been showing up a couple of times a day and I want to wait a few days longer before I consider the problem solved. Since this is an older very basic thermostat, I am thinking of getting one where we can program changes at specified times. Since we will be selling the house soon, I don't want the most expensive, rather something on the mid range level. Got any suggestions of one that would work ell with this Trane?
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| | Xenos
Webmaster
| "Re(5):emergency heat light on" , posted Mon 21 Jun 22:25
There all costly, I would check with home depot for a multy stage thermostat.
Xenos.
The best way to escape a problem is to solve it.
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| | blowout
| "Re(6):emergency heat light on" , posted Tue 22 Jun 07:57
It started again. Of course the aux heat light is not on but it stops cooling. I have the W wire disconnected. I am beginning to think the DFC board in the compressor has a problem. I did buy a new thermostat but did not have time to put it on last night. I will do that this afternoon. I suspect the problem may continue. If it does, is the next step the DFC board. (I really appreciate the advice by the way!)
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