Toyota Repair: Toyota corolla AC intermittent, gauge readings, toyota corolla

Question
95 toyota corolla. AC used to blast cold air except in heavy traffic it used to shut down. Replaced fan, this problem stopped. Car sat for 2 weeks. First use AC was good. Second use, AC was dead. Overpressure relief valve stuck open. Replaced valve, vacuumed, recharged. No good. Replaced drier, vacuumed and recharged. AC worked ok, not as cold as before. But now the compressor and fan sutdown after AC runs for some minutes. If I manually turn off the AC at the dash panel and leave it off for a few minutes, it will work again when I turn it on again. It will work for 5-10 minutes and shut down again. Recycle, etc. It definitely works longer when the outside air is cooler (sometimes non-stop at night) and when on the highway and not in traffic. The AC is shutting down due to some control causing the fan and compressor to shutoff at the same moment, as if there is an overheat sensor causing this to happen.

Answer
The a/c will turn off if the engine is overheating so make sure this is not the case, if the temp gauge on the dash goes to anywhere near the 3/4 hot mark the engine is overheating and the a/c will turn off.
If that is not the case the first step is to connect a/c pressure gauges to see what the line pressures are with the a/c operating, this will give a good indication of what is going on with the system, it takes someone with knowledge of a/c systems to interpret these gauge readings so I recommend that you find someone that you can trust or at least appears to know what they are doing.