You can use "pump down" as only PART of the diagnosis!! Yes this will tell you how well the suction valves are working, but no 2 compressors will be identical.Originally posted by hvacdoctor
Thanks for the replies. ? about pump down test. Why don't you recommend the pump down test to check compressor eff? The reason is we installed a new compressor last year on the other unit it pumped down rather quickly -25psi while the unit in question took 2x as long to get down to -15psi??? Just curious about this.
Use the "time" it takes to pump down. Then shut it down and watch how fast it "leaks back" and how fast it takes for it to get to "operating" pressures. Use this information with with the compressor curve (amp draw) superheat and subcooling. with all this information you should be able to determine if the compressor is efficient or not.
My 2 cents...