Chevy Blazer A/C problem

[KELLY88]

I've got a 99 Chevy Blazer with a 4.3 sitting in the driveway. Trying to get it together to sell and found a problem with the A/C. The blower kicks on fine but it blows hot air. Found out that the compressor wasn't kicking on. I got an R-134 can of refrigerant with the gauge on it and hooked that up. The pressure was ok but a little low. I added some refrigerant anyway and the compressor started kicking on intermittently. It's on for 2 or 3 seconds then off for the same amount of time. The air doesn't get colder though. Anybody got any ideas? I don't want to add any more refrigerant cause the gauge says the pressure is already high. I also noticed that the gauge pressure went down when the compressor kicked on, then rose again when the compressor was off. Is this gauge very accurate and does anybody have an idea what is going on?

 

[KELLY88]

Anyone? It's hot as hell down here.

 

[177CIOfPureLove]

There is a pressure switch that kicks the compressor off when there is too much or too little pressure in the system. This is a failsafe designed to protect the compressor. That is what it sounds like to me at least. Does it hold pressure? If so i would investigate that pressure switch. My system was a tad low and it just kept cycling it for a few short seconds at best until i added more.

 

[KELLY88]

Not sure if it holds pressure. Like I said the gauge fluctuates. The pressure increases until the compressor kicks on then decreases until the compressor dies. Is that the pressure switch acting up or is something else going on?