My heat pump will not shut off after the programmable thermostat got wet from leaking water. The thermostat has been dried up and working. But wether it was set at off, heat, or cool, the heater was always on and pumped heat to the house.

The heat pump is a Carrier split-system typical in Texas installed in 1996.

Can anybody onthis forum point me to the right direction?

Thanks

 

Turn power off to the unit out side and inside. Take all wires off the tstat mark them down how they are on the tstat. Turn power back on. If unit dont run get new tstat. I think you need it anyway. If it runs check out the wires there. It dont pay to use a programmable tstat on the heatpump cause when it comes back on to up the temp in the home it will turn on the strips heaters in the unit to get back up that 2o or 5o in the home . ED

 

once again ed is right. replace the stat, and use the setback function for cooling only

 

Don't mean to sound like a smart alec but don't most HP stats have a smart feature that prevents backup heat from coming on during the warmup cycle unless extreme conditions call for it?

 

1. Programmable Thermostat

There were two AC unit. One for upstairs and one downstairs. The one downstairs functioned normal. Only the upstairs' had problem. I shut off the circuit breaker from outside house for both of them and swapped the thermostats. I then switched the circuit breaker back on. The upstairs' heat pump still won't work. And the downstairs' worked just fine. The conclusion was the programmable thermostat upstairs was okay.

2. Compressor outside house checkup

I checked both compressor's big capacitors and they actted the same way for charging and discharging. I'll swap the compressor control circuit board tomorrow to see if they are okay.

3. Condensor up in the attic checkup

So what's inside the condensor up in the attic? Should I look into it as well tomorrow?

Any new directions I should look into?

Thanks for the responses.

 

Ok you say tstat is good.Do you have a meter? Do you have 24 volts there at the tstat. Is the transformer good?will R to G give you fan only?? R to Y just outdoor unit Are there any fuses in the unit in the attic. does out door unit run and not the inside fan in the attic. Did water get into the unit in the attic then????

Check transformer first here . ED

 

1. I would say that the good thermostat from downstairs could not control the heatpump upstairs. The upstairs' thermostat could control the heatpump downstairs.

2. The attic area where the blower sitting wasn't getting wet.

3. The heatpump's blower in the attic was always on once the circuit breaker switched on no matter what thermostat syas. I didn't look the compressor outside with circuit breaker on. I'll check it tomorrow.

4. I do have meter that I used for checking the capacitor today. I didn't check if there was 24V at thermostat. I'll check it tomorrow.

5. I don't know where is the transformer. Can you tell me? I'll check it tomorrow.

6. When you say R to G, do you mean disconnect al other connections and leave R to G connection only to see if the fan will run? I assume that you mean the compressor control unit outside.

7. I'll check the attic blower/condensor tomorrow. I haven't looked it yet.

Thanks.

 

When you say it won't shut off.. Is it just the fan only? Always cooling or heating?

Have you tried w/ all the wires off the t-stat and see if the fan runs or not?

If everything still runs w/ the wires off (not touching each other) the t-stat inside the house, then you need to go up in the attic and see what's going on.

Trace the t-stat wire (small brown wire) into the air handler.. Turn off the power, and then note and remove the wires from the control panel on the air handler itself. Turn on the power and see what happens. You may have to push the blower door safety switch to get the power back.

If it keeps on runing w/ the t-stat wire off the unit, then you may have a bad board or relay.

 

I checked it again today and found the things as follows:

1) Just the heater and blower ran in the attic only. The compressor fan outside didn't run with power on.

2) With all the wires off the thermostat and after turning power back on, the heater and blower still ran.

3) I went into the attic and open the blower. Inside I saw the fuse on the board, blower control board, transformer, and relays.

4) Fuse was okay.

5) Transformer was okay. Power supply side was 230V AC and output side was 27.8 V AC. ( I checked the good one and it also showed 27.7V AC).

6) Once I removed all the wires ( including 24V wire) from the blower control board, after turning the power back on, the heater and blower won't run.

7) Jay, do you mean removing all the wires except 24V supply from the control board, to see if it runs with power back on?

8) I checked the relay and found 0V AC from the two front terminals and 93V AC from the front to two back terminals.

I then compared this to the good blower and found the 230V AC from the two front terminals and 112V AC from front to two back terminals.

At this point, I still dodn't know if it is a bad board or relay yet. I think I need to swap them next time to be able to tell. Can anybody tell what goes wrong here, board or relay? Or something else?

Thanks,

 

Yes, just the wires that is between the t-stat and the control board.

if the syste keeps running w/ the T-stat wire off,, then might be the board.

 

Look at the tstat wire here . Ring it out and see if its ok. Also put just the 24V power to the board but no tstat wires ED

 

Reported here are my new findings:
I swapped the air handler control board and sequencer relay between good and bad air handlers. The bad one was still bad. Once I turned the power back on, the heater and blower were on again with all the wires off the thermostat.

By now I know for sure that the following components are good:
A: Outside house
1) compressor
2) compressor's defrost control board
3) compressor's capacitor

B: Indise house
4) Thermostat

C: Attic
5) Blower's control board
6) Fuse on the control board
7) 24VAC transformer
8) Sequencer relay
9) Blower's capacitor

So what else?

Thanks.

 

Just what is what here ??????? cant you have a stuck relay in this unit ????????????? Ohm out the tstat wires for a short ED