OK, everything I tried didn't change a thing.

I finally took it in to a local Dodge dealer. They said the electrical parts checked out, but the high pressure on the AC was too low to trigger the transducer to tell the computer the AC was running. That in spite of the fact it was working well enough to get reasonably cold in the cabin.

So, they say they are replacing the compressor and the high valve. The compressor is only three years old and maybe 35,000 miles. I bought the car with a blown compressor and had it changed three years ago.

My guess is the H valve caused the failure of the original compressor and that it wasn't caught when they changed the compressor (I always thought it sounded funny), thereby wearing out the valves on the new one prematurely and finally ending in a state where it couldn't pump up high enough to trigger the computer to turn on the AC fan.

Thanks everyone for your help and suggestions. I don't have the car back yet, but their explanation makes sense to me and fits the picture very well, at least as far as I understand it.

 

Well I guess I'm more confused now than ever. The high pressure transducer won't cancel clutch operation until system pressure drops below 30 psi. If system pressure is below 30 psi, it's pretty much empty. I don't buy any of their explanation but I guess if it works when you get it back, problem solved.

 

Yeah, keep us posted. The AC in our van, '08 T&C 3.3L, is flakey too. The radiator/condensor fan doesn't turn on when the AC is running. The fan and relays do work. When the van is cruising on the highway, with lots of air flow over the radiators, the AC is stone cold. Around town, not so much. I was thinking to replace the pressure transducer next.

 

I'm not buying it either. Based on his complaints anyway.

Is this the reading from the guages or the high pressure (switch) transducer numbers in the scan tool data? They should have compared the two to verify the transducer was reading right.

 

Kallsop, the fan only runs when it has to, based on pressure. Possible you are low on Freon, they do have rear evap leak issues with that year.

And amen TN, and if they don't match, then it's an electrical issue. So your either low on Freon or have a switch reading wrong.

 

I have read about the rear leaks, and it's possible I have a slow leak. But, the fans didn't turn on even after a vacuum and full charge. No real motivation to fix it until next spring now, the weather has cooled a lot. When the time comes, I will search out the rear AC leak threads and check the pressure transducer.