The car is having problems continuing to blow cold air in a variety of conditions. It shuts off during acceleration and will not come back on for a few minutes. It will also shut off for long periods when cycling at various times. Jiggling the ignition will sometimes cause it to recover, as will turning the car off and on again - but not always.

I have checked fuses and relays and so far everything seems to be OK. I know it has enough freon as well. Is there a cycling switch that I'm not aware of or some other common problem?

I found an A/C system diagram today (thanks to another old post ) and am on my way out to see what I can figure out. I would appreciate any guidance on what the problem could be.

By the way, I'm out in Arizona and it is vital to life, liberty and pursuit of happiness to get this thing working ASAP.

I managed to get the A/C system going for awhile by opening the compressor relay and cleaning it a bit. It wasn't long before that quit again. This is the second relay I've had in there in less than a year. Any suggestions on what to look at next?

There are a couple of things to look at.

First, a faulty engine temperature sensor can cut the A/C out on that car, but it doesn't seem likely in your case. (It is a separate sensor from the one that supplies the ECU and has only a single wire running from it. Just check the resistance cold and at several points in the warmup of your car. It should remain constant but I can't remember at what value)
Second, the refrigerant pressure switch can cut it out. If you have an overcharge, acceleration could build the pressure to the point where the switch cuts the A/C out until pressure drops to an acceptable level.
Third, the compressor speed sensor on the back of the compressor can sometimes be problematic.

I wouldn't be too quick to blame the relay. I owned an '85 190e and had issues with the A/C, but they turned out to be relatively simple once I understood all the things that tell the A/C to work or not.

__________________
'96 C280 (gone)
'97 C36
'05 C230k

Based on your situation, I would suspect the engine rpm and compressor rpm are not in agreement. The compressor relay will cut off when the two rpms are not agreeing and will not cut back on until the ignition is turned off and then back on. This is to protect the belt in case of compressor seizure. Your belt may be slightly loose and when you accelerate causes a slight slippage on the compressor and triggers the a/c relay. The relay sounds like it is operating normally. Check the belt tension and make sure it is not oily. Good luck!

oops..forgot to add that the compressor clutch can give the same symptoms if it is slipping due to oily surfaces or too wide of a clearance gap when disengaged.