Heat pump: should outdoor unit fan be spinning?

[Presence]

I just closed on a house built not even four years ago. It has a Ducane system -- an air handler (do not know model just yet) and a HP12B30 heat pump.

Outdoor temp was 61, indoor temp was 63 and I turned on and set the thermostat to 70.

While inspecting the rest of the house, I decided to have a look at the heat pump outside. The coils on the outside were about iced over and I could hear the compressor running, but the fan was not moving at all. Just in case I caught it in defrost mode, I checked again five minutes later - no change.

Granted warm air was blowing out of the vents, but because the system is new to me and I have not figured out all the technicalities yet I cannot rule out the possibility the electric heat strips were on and doing the heating.

The fan not moving does not sound normal to me, but thought I would run it past you guys first. Service call in order?

[davefr]

Service call in order?

Yes!!

The only "normal" scenario for outdoor fan not running and compressor running is defrost but that's highly unlikley at 61 degrees.

Hire a good tech.

I'd shut the unit down until then. (pull the disconnect and shut off all the breakers)

[HVAC_James]

By turning the stat so high all at once its very possible that the heat strips came on to supply the heat. With a hybrid system the installers set it so if the stat isnt satisfied (by HEAT PUMP) within 15 mins (preset by installers) it will call for back up heat (heat strips) the heat pump will runn better if you only call for a few degree heat change. Its not designed for turning the stat up and down but a constant temp will be more efficient (read the manuel ) it will explain more

[davefr]

Sorry beenthere.

I didn't think that formulating possible root causes of the problem was giving DIY advice. However I now see how it could lead to DIY.

[Bsmith816]

one quick check would be to <We don't give out that kind of advise either>

[davefr]

its possible that when you turned the hp up that high it couldn't satisfy the stat within the preset time (15 mins usually) and that coused the heat strips to come on. heat pumps are much more efficent when left at one constant temp. not up and down. try leaving the hp set and when adjusting only adjust 1-3 degrees at a time.

I agree 100% but that would not lead to the outdoor fan not coming on. I think we agree that the system should be checked out.

[HVAC_James]

I agree 100% but that would not lead to the outdoor fan not coming on. I think we agree that the system should be checked out.

If the heat strips come on after 15 mins of load the heat pump would be by passed as if emergency heat was on. Once the stat is satistied its possible the unit will work as designed

[Presence]

Yes, but keep in mind the compressor outside was still running.

[davefr]

If the heat strips come on after 15 mins of load the pump would be by passed as if emergency heat was on

Sorry, but I don't see any "normal" scenario where the outdoor fan would be locked out but not the compressor. If the HP get's locked out it's all or nothing based on the contactor.

[HVAC_James]

are you 100% it was compressor? i would wait until stat is satisfied then see what happens. If its not working then call for service

[ucsac]

Sorry, but I don't see any scenario where the outdoor fan would be locked out but not the compressor. If the HP get's locked out it's all or nothing based on the contactor.Perhaps the compressor went out on thermal because the contactor welded closed on fire up.

[bspecker]

there are several reasons the fan would not be running. Call a technician that understands heat pumps.

[ucsac]

Tried to erase my response... Sorry. I thought the fan was going and no comp.

[hvac maniac]

Sorry, but I don't see any scenario where the outdoor fan would be locked out but not the compressor. If the HP get's locked out it's all or nothing based on the contactor.

Not true. The defrost board allows the compressor to be on without the condenser fan for a quicker defrost. A tech who knows heat pumps will quickly be able to tell if there is a problem or not.

[HVAC_James]

Now that the thermostat has reached its temperature is the heat pump working again?

[davefr]

Not true. The defrost board allows the compressor to be on without the condenser fan for a quicker defrost. A tech who knows heat pumps will quickly be able to tell if there is a problem or not.

Yes, but not likely at 61 degrees ambient!

[Presence]

Ok, I had some more time to look at things. This time I went to the house and turned on the thermostat to warm the house only two degrees. Yes, this time the outdoor unit's fan was spinning.

So I bumped up the thermostat a few more degrees. After a while, the heating strips kicked in... but again, although the fan outside was no longer running, the compressor was. The whole time (about 30 mins), it never stopped. So this still does not seem normal.

I will be having an HVAC specialist look at it, for sure.

[davefr]

Ok, I had some more time to look at things. This time I went to the house and turned on the thermostat to warm the house only two degrees. Yes, this time the outdoor unit's fan was spinning.

So I bumped up the thermostat a few more degrees. After a while, the heating strips kicked in... but again, although the fan outside was no longer running, the compressor was. The whole time (about 30 mins), it never stopped. So this still does not seem normal.

I will be having an HVAC specialist look at it, for sure.

No. Compressor on and fan off is only normal during a defrost cycle. (usually <<30 minutes!!)

I wouldn't screw around with it any more until you have someone check it out. Turn the thermostat on emergency heat and pull the HP disconnect for the time being.

Report back what the techs diagnosis revealed.

[beenthere]

Yep. Set the stat to emergency heat. And wait for the tech to fix it before using it again.