air handler noise

[AHI in AR]

I found a York/ Unitary Products air handler made in 2011 that was making an unusual (and pretty loud) noise when starting up and shutting down. It sounded like liquid flowing through a pipe, kind of a rushing/ pressurized noise. I'm assuming it had to do with refrigerant flow, but I never had this occur before. Heat pumps are far less common around here than gas furnaces, but this is still far from my first one.

So...is it normal, and what is it?

[Jim Katen]

I found a York/ Unitary Products air handler made in 2011 that was making an unusual (and pretty loud) noise when starting up and shutting down. It sounded like liquid flowing through a pipe, kind of a rushing/ pressurized noise. I'm assuming it had to do with refrigerant flow, but I never had this occur before. Heat pumps are far less common around here than gas furnaces, but this is still far from my first one.

So...is it normal, and what is it?

Whooshing noises aren't uncommon with heat pumps at the beginning and the end of cycles. It's just the refrigerant. Most of the time, it doesn't indicate a problem. If everything else was working fine, I wouldn't worry about the whoosh.

[inspector57]

Reversing valves used to make lots of racket and still do on certain models.

If it is just a definite "whoosh" that dies out in less than 30 seconds during start up, shut down, or transition between cycles, no problem.

If it persists during normal operation or the valve chatters after it changes over, then it would warrant a further look.