A 95 AC compressor has an extra electrical connector, on the compressor itself, that is not on a 96-99 AC compressor. Anyone know what this extra connector is for?

A 96-99 compressor on a 95 will not run unless the extra connection is shorted. Had it set up like that (shorted) and the clutch on the compressor went out and is grinding. I have another 96-99 compressor but if the failure was because of the rigged connector and not just a faulty clutchr, then will have to buy one for a 95. Don't want to install it and have it last 2 days but don't want to spend $$$ for a new one if I don't have to either.

There are different compressors. From my understanding (and I don't claim to know AC at all) is that there is a variable compressor and a constant run compressor.

That may be the difference you are noticing.....although as mentioned.. I wouldn't know. My only suggestion would be if the first one gave you problems, the second will probably do the same..... use the correct parts or rolling the windows down are probably your best options.

I am posting all this on behalf of a guy at work. He was given a 1995 Olds 88 with a bad motor and a 1996 motor. The 96 is now in the car using all the 95'* wiring. The compressor on the 95 was bad so he used the 96'* and rigged the connector. But the 96 motor had been sitting in the garage for 3 years so we didn't want to rule out a bad compressor right away but didn't want to rule out the rigged connector either. He said it looked similar to the sensor in the coolant line so he figured it was an over pressure sensor. I thought maybe designs were changed and after 95 the sensor was designed out, not needed. Could verry well be the constant vs continous run like you said and in which case it seems to me the connector would likely be at fault. I know nothing myself when it comes to AC. I'm sure the best way to go for functionality would be to get the right one. I was just hoping someone would say otherwise and a 96-99 compressor would work fine and could save some $$.

So is that pressure switch what tells it to cycle on and off?

I believe the pressure switch located near the copmressor is a high pressure cut out to protect the system from an over pressure condition. There should also be a relief valve to back up the hp pressure switch in the event of failure.