All Trucks, Campers, Trailers, RV's and Motor Homes - '00 Dakota A/C

I have an intermiitent problem with my AC in a 2000 Dakota.

It works great for a while, even on hot days. Then, it just cuts out and will come back on if I stop the vehicle, turn it off and go again (sometimes it will blow cold air after a few minutes without turning it on and off, but that is not the norm).

I have measured the low pressure side and this is what happens. When it is running normally, the low pressure is right where it is supposed to be. When it is not running normally, the pressure is at least double what it supposed to be (if I recall, 45psi normal, ~100 psi not functioning).

Any idea what this may be, any other suggestions for checks?

Thanks

is the compressor even running when its not working?

I am almost certain that the compressor has kicked off when the system is not working.

you probably need to probe the wires going to the compressor clutch to see if it still has good power and ground going to it when it acts up, its not uncommon for the clutch to fail and only work part of the time, but it could also be pressure switch that may be bad causing poor power or ground issue to compressure clutch.

On one occasion, while measuring pressure, I heard the compressor kick off and saw the pressure go up.

Does the system have to be evacuated to replace the switch? I would have to bring it into the shop to do that. I will look at the Haynes manual before I ask any other questions, thanks for the input!

most models have a shrader valve wich allows for switch replacement without evacuation with some exceptions if the switch is threaded into the expansion valve it would need to be evacuated first. if its just on the line or drier it should have a schrader valve.
you should be able to back probe each wire on the a/c clutch connector with a test light to see if it has power and ground but you should leave the compressor plugged in while testing, as a test light alone does not pull enough amperage on the circuit to prove that the circuit is good with the compressor unplugged.

Thanks for the info. I have not found the problem yet. The Haynes manual has a pretty good troubleshooting guide, however, I have not been able to get to a point where it actually kicks out (aargh, it only does it when I am driving). I let it run for quite a while the other day and the AC was blowing as cold as could be and never kicked off. I guess when I drive it, I will bring the multimeter with me and stop and measure if it dies.

Thanks again,