View Full Version : Unusual noises from inside hermetic compressor

06-09-2016, 06:53 PM
I have recently noted on quite a few occasions, whilst running up refrigeration units with hermetic compressors, some quite unusual noises coming from inside the shell of the compressor. The noises sound like liquid dripping and are really quite loud. I have experienced these noises on all kinds of units, from display cabinets to dehumidifiers and heat pumps, but have never been able to correctly determine what the noises are, and I seem to be hearing them more often. It has no effect on the performance but I am just curious. Of course my first instinct was to think it was liquid flood back, but it seems to happen when the charge has been weighed in, (capillary systems) or the expansion valve is metering correctly and achieving a positive, stable superheat. The other thing is, it sounds too loud to be a few drips of liquid refrigerant dripping into the crankcase and sometimes it even sounds like chip fat popping and sizzling. I realise that it's a bit of a weird thread but any ideas would be welcome.
Thanks in advance for your time.

06-09-2016, 08:02 PM
Lack of oil can cause noises in small hermetics.
When they are still, equalizing pressure makes noise.

06-09-2016, 08:40 PM
Liquid/oil hitting a hot splash plate inside the shell?