Here is an underappreciated tech tip when trying to troubleshoot an AC Compressor. Any good mechanic (and even alot of bad ones) will have gauge meters for the ac system. You really should have one if you are working on AC. Getting the high and low pressure readings can tell us alot about what is going on in the system.

High Side: The high side tells us what the compressor is pumping out. Anything over 150-200 tells us the compressor is pumping. Larger compressors for bigger vehicles could go as high as 300-350, but generally over 200 will give you some cold.

Low Side: The low side tells us what is happening at the low side of the system. Ideally we are looking for about 30. That tells us that the auto air conditioning compressor is sucking properly and the big key; that there are no restrictions on the low side. Many techs end up with 200/85 or something like that and assume its the compressor. The 85 tells us that most likely we have a restriction in the low side. Either at the AC Condenser, Evaporator, A/C Expansion Device or something else on the low side. Sucking is actually easier for the compressor, so it can be, but is rarely is the compressor.

Some other common numbers are 150/30. This often indicates the system is under pressured and need to be filled and charged to spec. Another common one is 300+/50. This is typically an overcharge on the high side and some pressure should be released although you have propably blown the compressor at this point.

Hope this helps clears up some basic AC system troubleshooting.