USAMuscle

OK I just bought a recharge gun to test the freon level and hooked it up to the low side of the system, and the normal pressure is between 25-45, and on mine the gauge was reading damn near 150, way into the red zone. According to the gun instructions, that means there is something else wrong with the system. Where is the high pressure switch you are talking about? I wonder if that could be the problem. Also something I've noticed when the car is idling with the A/C setting on max and the blower on high, the idle fluctuates, like a minor rev every few seconds. It only does this when I have the A/C setting on. Also to answer all of your questions, it doesn't blow cold at any time. It always blows the outside air temperature, so the A/C isn't kicking in at all. I guess I should look at the high pressure switch next...maybe that explains why it's reading 150 on the low side when it should be reading like 40. [&:]

Stanley

The high pressure switch should be on one of the AC lines. You have two, a high and a low.

I am not sure on how to test the switch itself. If it doesn't cost to much you could get one to try it and see.

cmarquette

USAMuscle, did you ever find out if this was the high pressure switch? I've got the same problem with it registering over 150 when I test it. I don't have any clue on this. Any suggestions?

MineralGreyGT02

You didn't say if the car was started and the compressor clutch was engaged. If the compressor isn't running it's normal for the high and low side pressure to be ~equal. (which would make the low-side way high, and the high-side way low.) Once the compressor has been running for a few minutes the pressure(s) should be at "spec".

Try following Stanley's advice: "If the compressor doesn't come on, one thing you can try is to unplug the compressor and get some jumper wires and go from the battery +and- to the plug on the compressor. It should come on. Then see if it starts to work properly. If it does you might have a bad high or low pressure switch. If it doesn't work I would prolly keep looking for leaks." This is a great shortcut and eliminates a lot of pressure switches, WOT switch, and the dash switch, etc...

Make sure the car is running and you have the A/C turned on inside the car when you jumper it... If the compresser clutch does NOT engage you have a bad clutch. If it does engage then you can check your pressure(s)...

Good luck!

USAMuscle

Thanks for the info. I haven't had a chance to check it out yet, but I know for a fact it's not low on freon. I think it's probably the compressor or clutch. I will be at the shop at my school tomorrow so I'll put it up on a lift and try to jump it, and I also have full access to Mitchell 1, Alldata, and Pro-sis to for info on checking the clutch. Hopefully it's just the clutch or compressor. At least then I know I can fix it myself. [&:]

cmarquette

Sorry MineralGreyGTO2... That was with the car running. It's my sisters car and she said the compressor never made any noise. She said she went to work, came back out, turned on the A/C and it blew warm air. I also discovered while testing the A/C that her battery is dying, so I'll be replacing that as well. I'm going to try the jumper idea on Tuesday, so I'll post my findings. She's also picking up a book for her car, so hopefully that will help with locating the high/low pressure switches and the plug on the compressor. I've never worked on a mustang before, just my f150.