I have a 1991 Olds Regency and occasionally the AC Compressor Clutch will not come on..... But when I disconnect the negative terminal on the battery and wait 30 seconds before reconnecting it, the AC Compressor Clutch will come on and it'll last several weeks, then you have to disconnect the terminal again and so forth....... what is going on?

What are the gas pressures? Any codes?

What carfixer007 said ^^^^^^^

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How many miles on the car?

How many miles have you owned the car?

Used to have issues with the low PSI switch and/or connector. you may want to check those. I'm assuming that when the system is working that it'* blowing cold.

Yes, blowing very cold.....I've replaced those and still have the issue.

The car has 325,000 miles and I'm the second owner of the car, but have had the car for 25 years.

Pressures are specs and there are no codes.

Pressures are good. Are the pipes in/out of the evaporator cold?

That is what is so frustrating about this issue....when the compressor is working, the lines are cold and sweating.......... then the compressor goes off and you have to unhook the negative post for 30 seconds..... it never happens while it is running, but the next time you start the engine is where the issue is.

I wonder if the clutch is taking a ****, causing high current load at the ECU, so the ECU shuts it off until the fault is cleared(battery disconnect)

If you can, let it sit overnight, use a multimeter and measure the resistance(disconnect the connector) at the A/C clutch. Then do it again when the a/c compressor stops again.

You should see somewhere between 2 to 5 ohms. Not 0.5K, or 2.5K or 1M.

Anything less than 2 ohms indicates a possible open, anything more than 5 indicates a short in the coil. And with it heating up and failing leads me to believe it is shorting out.