A/C woes

[mhuppertz]

Today the compressor started cycling super fast then it quit.
I hooked up the gauges and the suction side was way high at 115psi and the pressure side was 130 (low).
Been working great for almost two years....
Any ideas?

[ellis93]

Weird! Only two things can do that.....compressor or expansion valve,I'd say the exp valve stopped up causing over pressure and bombed the compressor. I've seen the desiccant bag bust in the dryer and fill the system with a sandy substance ruining the compressor by making valve grinding compound in essence.
Hope I'm at least alittle wrong

[mhuppertz]

Thanks, I think!

[Diesel]

Sounds like a clog somewhere if the low side is hitting 115. That is dangerously high. Are those pressures at 2000rpms? Idle number can be deceiving but not that deceiving.

[ellis93]

Sounds like static pressure at high ambient temps

[Diesel]

Sounds like static pressure at high ambient temps

Agreed. Shouldn't be continuous at 115!

[D-dog357]

It might be a chunk of hose stuck in the in-take side of the valve body if you have real old hoses like most of us do. Don't know if our hoses are subject to chunking or not but I know some are.

Bad vales in the low side of the comp can allow static pressure numbers even when the pump is running. A clog would blow a high side hose.

Does the gauge flutter at all when hooked-up ? That's the first sign the valves are headed south. Either way, the only way you get even pressure numbers in a running system is with broken/stuck valves.

If you do the repairs don't forget to flush the system with some kind of solvent (I use denatured alcohol and a blow gun). Flush the the dryer separately as that makes it easier and don't forget you have to remove the expansion valve to flush the system. System flushes in a can just wash most of the junk in to the dryer but not all of it. Dump it on to clean paper towels and see what kind of crap comes out. Any rubber bits means it time for new hoses.

Or you could just pay someone a thousand dollars to do the job and hope they do it right.

[mhuppertz]

Dead steady on the gauges.
Just checked it this morning and the gauge readings were good. Ran the A/C for a while at idle and the compressor clutch started to stutter again. When I rev it higher the clutch works normally.
I think this points to the cycle switch, which is good because I have one on the way!
I will update.

[mhuppertz]

Well, hades.
The cycle switch wasn't the issue...
Scratching my head trying to figure out where the issue is, because the A/C works perfect for about 4 minutes, then the compressor starts stuttering and eventually quits and the suction side pressure stays really high until the truck sits overnight.....

[ellis93]

What are the pressures on both sides when the comp starts acting up?

[Mark Nixon]

Temperature/Vibration sensitive clutch winding?
Bypass everything but the clutch, heck, just wire it direct and if you still have the stutter, you have your answer.

Mark.

[ellis93]

Temperature/Vibration sensitive clutch winding?
.

All true and what I was leading to.

A/C systems are a fickle thing and its pressures Are very pertinent info in diagnosing

[mhuppertz]

The low side goes way high. I thought about just direct wiring the clutch, guess that is next.

[mhuppertz]

Looking at the schematics, there is a diode in the harness by the compressor that keeps the power from flowing backwards when the clutch is energized. Maybe that went bad. It's too hot to work on it!!! I need to get it working because my electric fan on my Jeep won't keep up with 100 degrees and the A/C if I'm not moving the whole time.

[Mark Nixon]

Too hot?
Then this YouTube link from an older 1980's movie is for you:

http://www.youtube.com/watch?v=DpktBGInl60

Mark.