whining noise from heatpump in Aux mode

Hi all,

I have a 1 year old Carrier heat pump mounted in the attic for the top floor of my house. Whenever Aux mode kicks in, I hear a high-pitched whine, kind of like a muted dentist drill. When it exits Aux mode, I hear a wooshing noise, like from a pressure relief valve. After that everything sounds normal. The whine appears to be coming from the condenser outside and the wooshing noise sounds like it's comeing from the attic. Other than the noise, everything appears to run normally.

Any ideas as to what to look for? I had a heatpump in a previous house and it was never this loud.

 

The wooshing Id say is when the 4way valve opens and lets the freon like turn around in the pipe from heat to cool. I wonder if you could be a little low on freon.Is the big pipe hot when the pump is running if so it should be ok.

The whine outside is the condenser fan ok Id look at it and see.



ED

 

When it goes into aux mode, does the outdoor unit shut off or does it keep running? If it shuts down, you are hearing what Ed described. It is the equalization of refrigerant pressure in the lines. There isn't anything else up there except the fan.