This is Turtle.
There is probley a 100 ways to check this but here is just one way to look for it. Run the hvac condenser or cooler conderser for about 5 minute and get it running and then turn the condenser off and if the suction line gets hot back about a foot or more. It has bad valves in the compressor or inefficent compressor. Now if you can't get a differencincial on high and low forget it for this test for this test is for parcial ineffeicent compressors. I have found this to work on most any freon type compressor for a test. Now there is 100's of other ways to test which should be done to be sure. Also i would like to hear about the other ways you know about.
Stretch -- Darrel -- Yes Stormy --- Regular other everyday posters --- any respectiable hvac/r people what do you think ?
Now the subject is compressors today but any one can ask about a problem area in electric , plumbing, or home construction that they feel should be cleared up to know about that problem that comes up in the course of the work or repairs. Everybody has those little thoughts or problems with jobs or repair that they would like to clear up.
TURTLE