Cadillac Repair: 84 Fleetwood AC compressor not engaging, r 12 freon, amp fuse

Question
Follow on question to the thread below: Is the low pressure switch replaceable? It appears to be part of the compressor itself. Do i need to change the entire compressor unit? The clutch engages when I short the black lead to ground.
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Question
Recently degreased engine compartment. Immediately after procedure, AC compressor clutch not engaging. Power available to connector at top of compressor (20 amp fuse OK as well). Is there somthing internal on the compressor clutch that might be shorted due to water intrusion? Or, a separarate electrical control in the engine compartment that may have been damaged? Looking for things to check other than the fuse or power availability at the unit.

Answer
Check for battery voltage with a METER, NOT a test light at the DARK BLUE wire at the compressor.If you have battery voltage. Momentarily ground the black wire and see if the compressor engages. If it does, back track the black wire to the low pressure switch and replace it.  

Answer
Yes. it is replaceable, But you have to remove ALL the freon from the system and evacuate all the air iout of the system and recharge it with R-12 freon. OR you can just ground out the black wire but if you develop a freon leak the compressor will NOT shut OFF and you will destroy the compressor. NOT RECOMMENDED.