Looking for Help with my AC

[Kevno6]

I was happy I found this site, have looked other places but found no help. I have a 2002 Dodge Ram 4.7 and this year the air was acting up . Compressor was working but blowing hot air so here is what I did and what is going on. I went and had air serviced vacuumed, leak tested and filled. As soon as we started truck compressor didn't work and was told compressor was bad. Later in the afternoon drove truck home and the AC to my surprise came on and work for my trip home from work. Which at that point I questioned whether it was compressor and was looking for an answer before I dropped the money on one. At work the next day I scanned it and came up with a stored code p1598 ac pressure sensor curcuit hi voltage. I changed the sensor which there is only one on top of compressor but not sure if it was the problem. What I have now is AC will work great for about 1/2 hour and then compressor will cycle off, in about 10 mins compressor will cycle on again and have great AC and continues to do this. Compressor, Condenser I am stumped. Fuses and relays are all good and voltage to compressor is good. Any help would be great Thank You

[Dougflas]

monitor the voltage to the compressor clutch. If hook up a small lamp and run it into the cab. You also may have a marginal clutch gap.

[GM Tech]

Next time it is "off" when it should be "on" - pull over, let engine run, pop hood, use wooden hammer handle and tap on front of compressor- if it snaps on, then you have a worn too wide air gap- answer is to remove clutch drive, and remove largest shim and re-install such that air gap is about .020"

This is a more detailed answer- as to what was said above...

[Kevno6]

Is that a standard air gap .020". I will check it out tomorrow. This could actually cause it to engage and disengage I thought if it was worn it just wouldn't engage. Or is it just so slight that it goes either way. Thanks

[bohica2xo]

The clutch gap gets wider as things wear. Adjusting it is not difficult if you can get at the end of the compressor.

The gap should be .016 to .032 according to the factory. Setting it on the low side, even as small as .010 is fine as long as it does not drag when off.

The adjustment is done by removing the drive plate, and removing one or more of the shims behind it. Here is the factory manual for the SD7H15 compressor:

http://www.sanden.com/productlibrary/ma ... _rev_2.pdf

.

[Cusser]

If the AC clutch gap was off, or the AC clutch was intermittent, then I can see why a mechanic told you that the compressor was bad, as the AC clutch is not typically replaced "alone", whole new compressor typically installed. But your experience shows it does work sometimes, so when not working, visually see if the center part is actually turning still. If not, then carefully try the test detailed earlier, and also make sure that the fan clutch or electric fans (whichever your truck has) for the condenser and radiator are all in operational condition; these could also cause AC clutch slippage.

Also: make sure the nut or bolt in the center of the AC clutch is tight as well (engine off, AC switched on should engage the electric AC clutch to hold it, and tighten the nut/bolt). I had this happen on a vehicle where the AC clutch was slipping intermittently due to loose nut allowing the clutch gap to "increase". I had thought I'd be swapping on an AC clutch, turned out that a nut just needed tightening !!!

[Kevno6]

I removed clutch to look at clutch and I only have one shim in there. I have had the truck since it was 2 yrs olds and nobody would have removed 2 of them if there is supposed to be 3. Clutch is worn and I think I will order a replacement when I get it should I start off with 3 shims. Could I remove the shim in there and try it to see if it engages better till I get new clutch. Also will It be ok to just replace clutch or should I also replace pully pressed-in the pulley. FRoNT PLATE. ELECTROMAGNETIC COIL. Thanks

[Kevno6]

the condenser fan is working fine and I also cleaned condenser last night.

[mk378]

Remove the one shim and try it. Like someone else said, it's not too close unless it rattles or drags when off.

The magnetic force from the coil normally gets weaker as the coil gets hotter. Thus it is very common for a marginal gap to engage every time on a cold start, then fail to re-engage later in the trip as the compressor cycles.

[Kevno6]

I removed it and no drag, running for last half hour will take it out for a drive later and see. Thanks