2nd Gen Non-Engine/Transmission AC won't turn off

[JBAndersen]

I can't turn off AC. . Any ideas? Where to start looking?

Rotary knob for defrost/floor/etc works fine and air is directed accoring to how I set the knob, but the AC compressor is engaging and disengaging as if the rotary knob was left in MAX AC, AC or DEFROST, even if I select any of the positions where it shouldn't. AC system is serviced and AC is cold.



Does AC increase idle speed as on most gas vehicles?



The truck is a 98. 5 2500. I had a 99 earlier where the AC disengaged as it should when the rotary knob was set in the correct positions. On this truck the idle speed was lower than in the 98. 5 with the AC problem.

 

[RWelkner]

The contacts inside the relay for the a/c compressor could be melted together. Try switching the relay out with a known good one too see if this helps.

 

[Cummins Thunder]

In my 02 the compressor works in all but like two positions. I don't remember exactly, but I will check it out when I get in it today.



CJ

 

[gonehuntingagain]

In my 2000, the only position where the compressor doesn't cycle is when the knob is turned to blow out the dash vents (in your face) only. A while ago some of the guys figured out what wire triggered the pump and spliced in a switch so they could turn it off.