Copeland Scroll makes long squeeking noise when shut off

viper

I have heard it "squeak" a little right when it shuts down before but ignored it as another odd noise from a scroll. Today I was right in the yard and all sounded normal but when it kicked out, it made a squealing noise for about 20-30sec after shut off. I am puzzled and to add to that, I felt the line set and both liquid and vapor were cold. Liquid was sweating. The liquid usually runs a little warm..

I am wondering if this sucker indeed was running in reverse or what the heck. It is a heat pump but that should all be disabled. I know for a fact I cut the entire reversing valve out and not like these pumps are made to run in both directions.

biggles

if it was running backwards the suction just out of the compressor would be slightly warm.you have possible restiction on the LL at the dryer.oil might of tripped out into the lines with all this cold pipes,scrolls continue to spin on shutdown so they are equalizing thru the scroll plate chambers...if it sounds like when you double start your car might be lacking sump oil.next time your running it retrict the top discharge air on that condenser so the head bulds up sliding the garbage can cover off a little and feel that LL for temp change.running a higher then normal head will recover the oil back into the compressor when running it.

viper

Wellm all seems to be running normally right now. I watched the following cycle intently and ran flawlessly. Actually blow cold on me right now. Showing about a 18*DT, compressor sounds normal and shut down normally too. I have heard this noise before but not for this long. Not sure if the scroll just stops at a certain point and it is just equalizing pressures or what.

It was in my research that pre '95 compressors do not have a check valve and will reverse flow on shut down. This one was built in 1990.

beenthere

Check valve may not have seated properly when you heard it.