My wife said this happened to her last summer-after it had cooled off it ran again. Driving home Monday I was enjoying my ice cold AC and then noticed it getting warmer until it was hot. When I got home I jumpered the connector and the compressor came right on-and stayed on when I plugged it back in. Last year I replaced the pressure switch in the compressor-evacuated the system and even purged it with nitrogen. It only does this when it's super hot outside so I'm thinking it's my pressure switch in what I'm guessing is the accumulator where you charge it. Question is does this have a shrader valve where I won't have to evacuate the system? I think that pressure switch is opening when it shouldn't. Or is this a sign of other problems? My accumulator sweats very nicely so I don't think it's an internal component problem.

 

Have you checked the high side pressure when it's hot outside? It's possible the system is overcharged or you have an airflow problem through the condenser that's causing the high side pressure to be too high.

 

High ambient temps cause the system pressures to go up so as mentioned, proper condenser cooling and evaporator airflow is important as well as charge level.

The sensor/switch at the accumulator is the low pressure/cycling switch. I believe that this accumulator port almost always has a schrader and that the high pressure switch at the compressor does not. You can defeat either switch temporarily for diagnostics purposes.

George

 

I have had my Blazer do this a couple of years over the last five - intermittent compressor engagement issues. Cure each time was replacing the low pressure switch, which for some reason came out with a bunch of compressor oil in it both times. I suppose maybe my Blazer has too much oil or too much Freon in it. But these switches are cheap enough that I just replaced them instead of trying to dump the oil out and make them work. This switch is on a Schrader valve, so you can just twist the old one off and screw on the new one without losing Freon. Let me know if you experience the low pressure switch full of oil thing too. Just up-end the switch and tap it on a piece of paper.

 

I replaced the switch, and a little bit of oil (not much) sprayed out with the pressure until the shrader valve closed. There was a little bit of oil in the old one that I used to coat the new o-ring with. I ran it that afternoon without any problems in our 100+ degree weather. The real test will be driving in our lovely bumper to bumper rush hour traffic when it's 100+ outside. It's mercifully cooled off today though. The reason I don't think it's over pressure is because when it quit last week I immediately jumpered the compressor and plugged it back in without letting anything cool down and it ran. Now I've got to figure out what's squeaking after replacing the fan clutch, tensioner assembly, and idler pulley. If there's not a small problem creep up when you fix another, then you don't own a Blazer. It's a love/hate relationship that's for sure.