My 1994 built home has the original heat pump. When placing the unit in regular heat mode, it makes a loud thumping very close to the Jumanji movie drum beat. I'm not kidding and is very loud and can be heard from any home within 200 feet. The only way I can get it to stop is turn the unit off or place it in Emergency heat mode.

I had a technician take a look at it last year and he he thought the refrigerant was low and added some. This didn't help the issue and unfortunately the unit wouldn't make the noise while the service technician was here.

The unit works fine for AC during the summer without the noise and only makes it in regular heat mode after being turned on for about 15 minutes.

Any thoughts?

Bill H

[email protected]

Is this noise coming from the outdoor unit or the indoor air handler? You didn't specify. If it is the ODU, go out and check if it is the fan or if you can localize it to a part that you can see inside the unit. DON'T open it up. Is the sound in the tubing and transferred inside that way?

EPM

It just occurred to me that it could be liquid slugging in the compressor. If that is the case, it will soon be ruined if it keeps up. Call a repairman. If he hears it he should be able to diagnose it.

Broken compressor internal spring?

The noise is coming from the outdoor unit and seems to originate from the tubing with a pulsating/thumping sound. If seems to be worse... noise start sooner when the temperature is colder. If it's liquid slugging in the compressor or a broken compressor spring, is there anyway I can troubleshoot myself or must I call a service technician.

Unusual that this only occurs in the heating mode... does the large insulated line get warm/hot when the heat pump runs (carefully check where the copper is exposed, while noise is occurring)? If the heat pump utilizes a scroll compressor, and the reversing valve is leaking through in heating mode, the under-loaded scroll may be slapping around. Did the technician check the operating pressures in the heating mode?

I have an outside Heat Pump unit that has begun to occasionally make a loud audible thumping sound when the HEAT is turned ON. I just noticed it making the noise beginning this fall, when the weather is cold. It didn't make the noise when the AC was running this summer. It was originally installed in '91.