OK, my A/C isnt working, and I'd like to fix it myself if I can..

Its holding pressure, so I dont believe its leaking, my gauge is showing it to have good pressure sitting and while not-running..
The clutch wont engage, Ive checked the fuse and relay, both appear good..

Where is the low pressure limit switch located? I looked, but it isnt obvious..
I want to by-pass it and check the clutch and freon charge before shelling out the bucks for someone else to do it..
a pic would be helpful..
Thanks!

 

I don't have a pic, but it's on the high pressure line.

 

Don't know right off hand if it's high or low side, but there is a cut-out switch down by the compressor. I'll go take a look here in a bit and see which it is. What are your static pressures with the truck turned off?

 

Mad is right, it is on the high side. Right next to the compressor. Might Ohm the clutch coil and verify that it's okay.

 

Man, if I had a dollar...

 

It is actually an high/low pressure switch. Either one can cut the compressor off.

 

I'll leave that one alone!!

 

Did you ever get your A/C to work????????????

Let us know, I'm kinda curious since you say your static pressures were OK.

 

J, I have had some other things "blow up" and havent even thought about messing with this yet, Ill let you know once I get to it..

 

Hopefully the "blow ups" are NOT on the truck you just purchased!!!! Let us know if there is anything we can help you out with........of course, you already knew that.

 

I had AC problems last summer and yours might be like my 03. IIRC, there is a low temp cutout mounted in the evap coil - no lo press. sw on the low side line. The switch in the disc. line is a trinary switch. I think I know what it does but I wouldn't bet my life on it! I think it is a loss-of-charge/cooling fan control. Do a search on AC trinary sw. Many residential ACs use a loss-of-charge (pressure) sw on the hi side instead of the old lo press safety on the lo side. The evap stat is the lo temp safety and the trinary sw is a loss of charge safety so the compressor won't pump out all the oil. I was fretting having to pull the evap to replace the lo temp stat but it turned out to be another problem. I've read there is no engine fan control from the AC but that's not true. I watched the head pressure cycle up and down, very consistently as the fan cycled, and I think that was from the trinary sw. Does your compressor light on the dash come on? I think that light is a true indication that the clutch has power. Have you checked for damaged wires at the compressor? I found a shop manual disk for $24 when I had problems but it doesn't explain every minute detail. Craig

 

No, they were with the house... flooded basement and heating boiler issues..

I found that if I jumped between the 87a and 30 "pegs" of the clutch relay, the compressor would kick on.. Jumping from the battery + to the switch leg of the relay got it working, so the problem appears to be the in-dash switch..
Dealer quoted me $600 for the part today!!
I was gonna just by-pass the factory switch with a cheap one from O'reilly's, BUT this afternoon, it suddenly made a loud squealing sound and vented refrigerant( couldnt see where from, hood was closed)
Clutch will still engage and run, but no cold air, guess I have another issue in the lines as well.
It was holding 40 psi on the low side@ idle, at 75*f ambient air temp, and working well yesterday
Im guessing there was a blockage in the lines, and getting it running built pressure, possibly blowing out an o-ring?
I cant afford a big repair bill on the truck, having just paid out for repairs on the house... guess I am sweating for a while..

 

40psi on the low side is a tad high..... for my liking anyhow. I like the low side to be between 10-25psi. Look at all of your A/C connections and see which one is oily....that will tell you where your leak occured.

I replaced my compressor (brand new), cold line, and accumulator for under $400. Pulled a vacuum, charged it up, and been freezing ever since. O'Reilleys had all the parts so I was without air for a total of 2 days. It was never right from the day I drove it off the dealership lot.....always froze up but for some reason they could never diagnose the problem!!!!

I kinda lost faith in them pretty quick. Had several u-joints fail and they could never figure that one out either....HELLO.....the dang things were practically dry when they installed them!!! Anyhow, hope you get it squared away. I'll try to answer any other questions you may have Chris.

 

What I need is an explanation of how the power runs from teh in-dash switch to the realy.. its apparently not a simply "on-off" switch in the dash..
when the dash switch is depressed, the compressor light comes on, so there is power to it, but it is not receiving power at the switch leg of the a/c clutch relay.

 

Have you verified that the relay is good? You're just not getting 12v to the relay....correct?