Got some issues with the A/C in my truck here's what I'm working with, any help would be greatly appreciated.


On initial start up, when I turn the A/C on it will cycle rapidly on an off until the truck warms up to operating temp and then it stays fully engaged. during the warm up period, the clutch on starts to blow cool, but as soon as it kicks off, it's really hot humid BO smelling air. When the truck gets up to operating temp, the A/C is fine and cool.

The Manifold Gauge stays equal pressures at 44psi with the truck off (for at least 3 hours), so I'm assuming there's no leak in the system or it would have dropped correct?

When testing the A/C with the truck on, the low side gauge is reading 15psi and the high side is at 65psi. At the 104* temps we've had, that's way too low. The clutch shouldn't even engage. The FSM (pg. 2732) states I should be at 60-70 PSI low side and the high side should be at like 270-330 PSI, that should bury the needle on the manifold gauge set I have. I added an entire can of R-134a and the pressure barely moved upward. There's no way I should have been able to add 12oz of freon to the system, if I had cool air before.

What the hell is going on???

 

vacuum system check valve. I got the same problem just cant find out where it is. Somewhere right before it goes into the firewall.

 

The vacuum system check valve is the elbow **** that plugs right up to the intake manifold that has all the vac lines running off of it. Passenger side on the 2001 dead center of the intake manifold, just under the TB bracket.

Just out of curiosity, how did you diagnose that part?

If that part was faulty, wouldn't it affect all the vac accessories that come off that line?

Edit: there's also a small T in the line further up, that's the other valve, that's the one that needs to be changed out. Just follow the lines up from the intake manifold and look for the plastic "T"

 

btw, that's not my problem. anyone else have some ideas? I'm guessing the compressor may be biting the big one.

 

i had a similar type problem. I had to acctually put a jumper wire in the connection that goes into the black tank lookin thing by pass firewall. That keeps the compressor running and i get cold ac. If it aint runnin, it just cycles on and off constantly.

 

Do you see anything coming out of your vents?Whitish flakes? Common problem with the evap core going bad.

 

yep, I've seen flakes shooting out, but isn't that snow or ice when the evap core goes? Guess I should try to catch some of it, might be time to rip up the dash and do the heater and evap.

 

Motorbrreth: Using a jumper wire on the dryer/accumulator(Black tank thing) is defeating the purpose of the siwtch you have by-passed. That switch is a low pressure switch designed to cut out the compressor when the charge is extremly low so that you don't burn up the compressor. If your compressor is cycling rapidly then you have a low charge more then likely. Have it checked.