I am an certified ASE air conditioning tech, with about 10 years experience. No expert , but I paid my $10It's intermittent and hard to pin down. I know it's electrical but don't know enough about the A/C system to properly troubleshoot it. The compressor will just shut down. Sometimes it will come back on after a few seconds and sometimes it will take anywhere from five to twenty minutes. I checked the R134 charge and it's fine. At first, I thought it was the relay but after replacing it, I still have the problem. Then I thought it was the relay socket because the relay would open and close after wiggling it so I put some different connectors in the socket and hooked them up to the relay to make sure it had a good solid connection. After this, I still have the problem. The weird thing about it is it only seems to happen when it's hot outside and sometimes it will happen after I give it a lot of gas like when I gun it to get around someone. It doesn't ever happen at night when the outside temp cools down and it always happens when I'm in stop and go traffic. I'm really scratching my head over this and don't want to spend the outragous prices to get it looked at by a professional...What do you know about how the A/C works?
There are some things to check.Is there a pressure switch somewhere that could be going bad ...
First the basics. Pull your grille to check the condenser for debris. Bugs , mud , dirt, chaff, etc. Then take loose the top fan shroud so that you can look in between the radiator and the condenser for the same debris. Cleaning this alone may fix your problems. A plugged up condenser can create overheating problems and an overpressure situation triggering the high pressure switch shutting down the compressor.
The condenser must be clean for the freon to make the change from gas to liquid and effectively dissipate the heat it is removing from your interior.
Now look everything over for signs of a leak. You will see an oily residue where the leak occurs as the refrigerant oil is the first thing to go. If there is a little dust it shows up pretty easily. Check around the hose connections, compressor clutch and filter dryer/dehydrator.
Next you need to check the electrical connections. You are right there is a low pressure switch over by your filter dryer (the aluminum canister near the heater/AC box on the firewall) It has two wires going into the top of it.
This will be tough, but you need to check this when you are having a problem. When the AC is not working and the clutch does not engage. Cut a two inch long piece of wire , strip the ends and use it as a jumper. Detach the connection to the low pressure switch and insert the jumper. Does the clutch engage? If it does everything else is OK in the electrical system.
The next thing you need to do here is check the pressures. This will require seeking the help of a tech, since you probably won't have a AC manifold gauge set lying around. If the pressure is up , then you are full of freon and the switch is bad. It is not all that common for the switches to fail , but it can happen. It is more likely for the system to be low on freon due to a leak.
Now for the rest of the electrical connections, should the clutch not have engaged when you jumpered the low pressure switch. On the back of the compressor is the high pressure switch. You need to test this with a multimeter. Unplug the connector and check for voltage in the light blue wire. This is the AC request wire and should be hot when the controls are in the AC mode. Next check the switch on the back of the compressor for continuity using an OHM meter. There should be continuity. The switch breaks it's connection when the pressure threshold is exceeded. If both of those check out then I would say that part is OK. I have only seen one of those fail in my experience.
Next is the compressor clutch if the other two check out and jumpering the low pressure switch didn't work. Try it again and test the connection to the fan clutch for voltage. If there is voltage and the clutch does not engage. Then the clutch is bad. I haven't had this happen. Usually when a clutch goes bad the bearings fail, it seizes, or catches fire. Pretty obvious things.
Of course check all the wiring for bare , shorted , damaged wiring.
That is probably about all you can do. If you are still having problems, you're going to have to see a mechanic. Keep in mind that they are only going to be able to fix what is broken. Intermittent problems are a real pain. You need to be able to repeat the problem for the mechanic.
Best of luck. If you carefully check everything above you may indeed narrow things down for a mechanic to repair, and save yourself quite a bit of shop time
Its been over 100 for 27 days STRAIGHT here, and my compressor went belly-up apparently.. Messed with it a little sunday night, it almost turned a full turn without killing the engine.. but the day before it would kill the motor dead when the clutch engaged on the pump.. Wish mine was a s easy to fix as the possible overheated ones 