air conditioner does not operate after compressor replacement. 1993 240SX conver

[winddriven1]

1993 240sx conv. A/C stopped putting out. Went to my friendly auto shop which has done well in the past. Put in new A/C, supposed ran through system, A/C worked for four months, then stopped working. Second compressor put in. Friend tells me about the Thermo Control Amp. Got one from dealer for $25, put it in. Still no A/C but compressor appears to have died again.

Question: Can that thermo control amp have any bad effect on the compressor's functioning, that is, if the amp is bad, can that kill the compressor??

Cause the "friendly auto shop" is saying they can't warranty their work, must be something else wrong with system. I'm getting the short straw here, I think. What say you?

[driftingmy240sx]

the termo amp prevents evaporator case freezing and will cancle the compressor on signal till the evaporate thaws. are there any leaks? was dye put in the a/c system? is the compressore recieving the 12 volt signal to activate the clutch? is the clutch failed because its a cheap aftermarket part?