Weird AC compressor issue

[hshift]

It's been a hot summer so far, and I've been having a weird problem with my AC. Every now and then, the compressor will refuse to come on. The only way I can get it to come on is by disconnecting the battery for a few minutes. When the battery is re-connected, the AC works fine and is blowing cold and strong. Usually a few days later though the compressor will not engage, but everything else is OK as far as air blowing thru the proper registers and all, and there is no flashing of the controller display. I have checked for codes thru the controller, and the only code I have seen is 152, which is short term memory loss, (maybe from my disconnecting the battery?) Sometimes the compressor will engage for a minute or so while I am toggling thru menus on the controller, but only disconnecting the battery will keep the compressor running for any length of time. An example of my problem occurred just this week. Last Sunday I parked the car at the airport, and the A/c was working fine during the 30 minute trip there. One week later when we returned from our vacation and got in the car at the airport, the compressor wouldn't come on. I have changed the HVAC programmer with one I got on Ebay, but the problem is still there. BTW, this car is a 1991 Ninety Eight, the AC is R134 converted two years ago.
Any ideas out there? Thanks in advance!

[maxwedge]

Many things can cause this, I would suspect the control head, or possibly the compressor relay. A comprehensive trouble tree from a GM manual is the only way to track this accurately, when it occurs of course.

[hshift]

I put a new relay in awhile back, so I don't think that's it. I'll hunt around for another control head. Thanks!

[hshift]

Finally found a new control head, no change. Compressor will choose to run when it wants to. Gonna break out the GM service manual and do what Max says to do.

[brcidd]

Sounds like you are setting a code 46- low charge-- your system counts the compressor cycles and shuts it down to save the compressor if there are too many in too short of time-- the code is read by a scan tool only- and can be reset by the scan tool (Tech I) or by disconnecting the battery as you have already found out-- I once spent 5 hours on a '91 C/H car (as is yours) and finally though to read the codes in the ECM - not the control head-- double check the amount of refrigerant in your car- the only way is to take out the refrigerant and weigh it-- my bet is that you have about 1/2 the specified charge in there- most likely leak location on your car- is the compressor shaft seal and the evaporator core....