jay wrote:
I bought a Friedrich 40 pint dehumidifier. It makes a whistling noise for a
few seconds when the compressor starts up. The whistling noise does not
seem to happen if the unit wasn't run for a while. The noise sounds a
little bit like a tea kettle whistle and sometimes alternates between a
higher note and note that is maybe a major 3rd lower to a tritone lower.
The pattern is Higher Note LowerNote HigherNote then no whistling.
Sometimes it's more of a constant tone. Anyway the noise goes away after a
few seconds. Is this normal?

J.



This is because of the high pressure being generated by the compressor
upon startup. The noise is different after it's been on awhile because
now there is some residual pressure. It's probably perfectly normal.
As for the unit you returned - why did you return it?
If it was not functioning properly because it was freezing up or not
dehumidifying then the reason it didn't make the noise is maybe because
it never generated the correct pressure within the sealed system in the
first place.