Would a heat pump do this ? Have not seen before

[Gene South]

I inspected a 10 year old house with a heat pump. Outside temp was 38 degrees. Inside was 60 degrees. I went to the thermostat and set the temperature to 61 and the condensor did not come on, so I set it to 62 and the condensor came on. I went outside and noticed the condensor was loud and then noticed the fan was not moving. I turned the unit off. On my way inside I was wondering if the condensor fan could be themostatically controlled to not spin in cold are (outside air temp was 38). I dont think that is the case but I have been wrong before. Has anyone seen a condensor that the the fan would not come on in certain temperatures ?

Gene

[Vern Heiler]

Gene, it is possible that the heat-pump was in defrost as soon as it came on. It is more likely the outdoor fan was seized. The quick and dirty way to tell is to feel the temp of the gas (large) refrigerant line at the out door unit. If it is in defrost, it will be cool (not cold). If it is in the heat mode, it will be warm (approaching Hot). Also if the fan is seized you can normally feel the top of the unit where the fan mounts and it will probably be hot if its seized.

[Jim Luttrall]

VH nailed it, Sounds like defrost to me.
The fan will be off during defrost but would not be thermostatically controlled during the heating cycle.

[Gene South]

Jim and Vern, I forgot to emphasize that the compressor was noticabley very loud...made me think it might seize up. How does that sync with your thoughts on this unit?

Thanks

Gene

[David Bell]

Is it possible that the fan motor was making all that noise? There are units that operate the fan by pressure, but not likely on a ten year old residential.

[Gene South]

Dave, I am sure the noise was from the compressor, not the fan.

Thanks

Gene

[Vern Heiler]

Jim and Vern, I forgot to emphasize that the compressor was noticabley very loud...made me think it might seize up. How does that sync with your thoughts on this unit?

Thanks

Gene

If it was in the first part of the defrost cycle the compressor does make extra noise for a short time while pressures equalize.

One other thing that can make a lot of rattling and maybe sound like a bad compressor is a bad contactor relay. A bad relay would prevent the fan from running as well as the compressor.

[Jim Luttrall]

Jim and Vern, I forgot to emphasize that the compressor was noticabley very loud...made me think it might seize up. How does that sync with your thoughts on this unit?

Thanks

Gene
Normal if you caught it just entering defrost. Of course I was not there but it is normal for them to get noisy during defrost as pressures change. Mine wakes me up on occasion just due to the change in sounds from the outdoor unit.


I inspected a 10 year old house with a heat pump. Outside temp was 38 degrees. Inside was 60 degrees. I went to the thermostat and set the temperature to 61 and the condensor did not come on, so I set it to 62 and the condensor came on. I went outside and noticed the condensor was loud and then noticed the fan was not moving. I turned the unit off. On my way inside I was wondering if the condensor fan could be themostatically controlled to not spin in cold are (outside air temp was 38). I dont think that is the case but I have been wrong before. Has anyone seen a condensor that the the fan would not come on in certain temperatures ?By the way, the outdoor unit is not the condenser... during heating (except during defrost) which is the reason I try to use "outdoor unit and indoor unit." The condenser is actually inside during heating operations;)

[Gene South]

Hi Jim, yes. good point. Thanks

Gene