I've got a Bryant 661A Heat Pump with a Honeywell T841A thermostat. Here are the symptoms:
- Works flawlessly in COOL mode
- Problem only occurs in HEAT mode
> Green LED (AUX HEAT) on thermostat flashes on/off at ~ 1Hz rate
> CHECK and EM HEAT LEDs are OFF
> Clicking sound coming from outside heat pump that corresponds (sound synchronized with frequency of LED flashing) to the green LED flashing
> Validated clicking sound is NOT coming from contactor
> Problem is intermittent, may only happen once or twice a day
> Problem occurs both above and below 32 degrees
> Fan on heat pump is turning
> Unit will eventually stop exhibiting symptom after several minutes (heat pump kicks off)

Any suggestions to further troubleshoot or identify probable component failure would be greatly appreciated. This problem started last Winter and I noticed it reoccurring this season after I switched to HEAT mode. Thanks!

 

Sounds like the stat is kicking it from heat pump mode to auxillary mode. The clicking outside is probably the reversing valve.

I always hate to condem a t-stat but that's what it sounds like.

 

You could try and feel the copper lines. To see if its the 4 way valve. The big copper one should be hot on heat. On most units the 4 way valve is in heat mode all the time and should only be in cool when called for AC. Thats so if they fail you will have heat. Im like Matt I dont like to say its the tstat but on the programmable ones who knows anymore.

ED

 

I have a 2 zone system in my house (upper and lower floors with the same tstat). Just to eliminate the tstat from the possibilities, I'll swap the tstats and see if the symptoms move to the other unit. It's suppose to warm up here over the weekend (mid 70s). So, I probably won't be able to verify anything until next week. I'll keep you posted. Thanks!

 

Do you have two units there are one unit and two zones?

ED

 

They are 2 completely independent units (I can see how my previous statement confused you - I should have said the same tstat MODEL). Here's clarification on my setup.

Tstat on the 2nd floor controls the air handler in the attic and heat pump #1. It supplies heating and cooling to the 2nd floor.

Tstat on the 1st floor controls the air handler in the basement and heat pump #2. It supplies heating and cooling to the 1st floor and basement.

Finally, this is NOT a programmable tstat

 

It wasn't the tstat.

The problem became less intermittent. Therefore, I was able to perform some real time troubleshooting. The length of time the unit remained in the cycling state (< 5 minutes) led me to the defrost circuitry. I verified the defrost temp switch was closing at the time of the failure. However, the voltage at the Reversing Switch was cycling up and down (I used a DVM - the display was jumping around). To eliminate the temp switch, I shorted out the pins leading to it, but the problem did not go away. Therefore, I had either a bad RVS (that was drawing too much current and causing the voltage to drop) or the control board was defective. I chose the cheaper of the two and replaced the board.

It's been running without a problem now for over 9 days. I believe I can close this case (knock on wood).

 

Hey you did good there. I think you mean the reversing valve there . It was the next thing to work on. Just "INFO" you can buy just the coil for them dont have to go into the feron lines.

Have a warm HO HO xmass

ED

 

Thanks Ed. I did mean the Reversing Valve (not switch). Also, thanks for the 'INFO' tip. Hopefully won't have to go there.