I have a goodman heatpump.

It works fine in cold mode.

When in heat mode it started blowing cold air this morning. I cycled it off and then on again and it worked ok. The next time it came on it blew cold air again.

The inside and outside fans work ok. When in heat mode if I turn the set point up and down the unit comes on and shuts off properly (except blows cold air sometimes)

There is no ice inside or outside. I checked the contactors and they seem to be making up properly.

The tstat is a simple on off heat / cool mode thermostat with no lights or led's. I did try running the fan only for a while and had no luck. When it does blow heat it works great then next cycle may blow cold. Hate to wake up in the middle of the night and it's 50 deg.

I'm suspecting reversing valve or tstat. Any help would be appreciated before I freeze!

 

It seems that the unit when running in heat mode works fine then goes into what I believe is a defrost cycle and never comes out and just stays in cool mode.

 

You have a heat pump, but no control over the auxiliary heat at the thermostat?? Is there any auxiliary heat? Was a new thermostat recently installed?

Not sure what normally ends the defrost cycle - the ones I've had were timed. If Goodman is similar and defrost isn't terminating, it's probably the board in the outside unit. Others might be more familiar with the brand. I would call in a pro. Could be multiple things going on here. If you have auxiliary heat, it doesn't seem to be working correctly either.

Doug M.

 

We live in AZ so I guess they decided Aux. heat was unecessary. There is no gas in the subdivision and I don't believe there is an electric backup.

I'm gonna try to check out the tstat today and also see if I can tell if the reversing valve is actually getting a signal to close or not.

 

Most units today the 4 way valve should fail in the heat mode. It should only work for defrost and for cool. When you say it blowes cold air is the outside fan off. Could jump R -Y-G see if you get heat. All units should have back up strip heaters to warm the air when they go in defrost mode and as Aux heat if compressor goes out.

ED

 

I climbed into the attick and pulled the cover off. The brown and white wires for a heat strip go no where. ie: no heat strip. I pulled off the cover going to the outlet and saw no heater.


All parts of the system seem to be operating normally except blowing cold air in heat mode. All fans run normally in all modes. I jumpered the R-G-Y. Fan and comp. run normal. If the reversing valve fails in heat mode I'm starting to think I can rule it out. Now I just need to determin why it goes to defrost and stays there. Is there a timer somewhere (other than on the air handler)?

I really appreciate everyones help.

 

Did you get heat with the R-Y-G????? Should have a defrost board in outside unit.

ED

 

R-Y-G gives heat. Since reverse valve should fail to heat I think I can rule it out. I'm now thinking one of the defrost ralays on the defrost controller or maybe a defrost thermostat (thermocouple?)

We may get this licked yet!

 

All the defrost controls should be on the board in the outdoor unit. Probably just neet to replace the board.

Doug M.

 

if the unit is going into a timed defrost cycle, and you have no aux heat, i would expect cold air, since the unit is in a/c mode.

if it is sticking there, it is a termination problem, some are time controlled, others temperature.

have seen goodmans do this with a bad board, but be sure the sensor is secure to the line in the outdoor unit

 

if it is sticking in defrost, be sure the sensor is attached to the coil outside, it will have wires will lead back to the defrost board.

if they are 10 minute or less blasts of cold air, the problem is probably no strips to temper the cold air, as it is in ac at this time

 

Ok here is the deal. I tested the defrost thermostat and it is closed. I ran the system in A/C for a while and tested it again. Still closed. I ran it in heat mode for 30 minutes (timer is set at 30) and it went into defrost. None of my neighbors machines are going into defrost. It is now 48 deg outside but it was around 55 today.

Anyway, I pulled the wire off of the defrost thermostat while in defrost mode and it went back into heat. I didn't wait to see if it would time out of defrost in 10 minutes because it was getting cold in the house and I just paid for all that heat! Tomorrow durring off peak time I'll let the defrost go for the 10 minutes to make sure it is working but I'm pretty sure it is the thermostat.

Am I crazy or am I on track?

One last question, while in defrost shouldn't the compressor fan shut off?

Thanks again for all the help.

 

Well I disconnected the thermostat on the defrost circuit and the heat pump works fine. I've tried putting the thermostat in the freezer and also heating it up and the circuit is closed so I assume it is bad. Since the dew point here in Phoenix is almost always below freezing in the winter I don't think the part will be missed for a while. This must be the same reason there is no aux or emergency heat since it almost never freezes and the unit should never need to be defrosted.

Thanks again for all the help.