1999 Dodge Ram Van A/C, Heat Temperature Control Issue

My 1999 Ram Mark III Conversion Van with a 5.2 engine is experiencing a problem. The temperature control knob that makes the air blowing out from cold to hot does not blow out cold when the A/C is on and the knob is all the way to the cold side. It's cool but not cold like it used to be. Then if I barely move the knob towards the warm side it starts blowing out very warm. Is there anyway to "reset" this so it can work as it's supposed to? Or does anyone know what the cause of this could be and how I can fix it myself? I appreciate the help and think this is a great forum for us Dodge owners. Jim

Hey seasharp;


Check my post under "Air Conditioning Controls" Basically it was a vacuum leak.

bobo35

If it's not a vaccum leak like bobo said, then it's possible that your A/C system needs to be re-charged with R134a. I have to get that done for both of my Ram Vans too since temps hit 92 degrees here the other day.

If you have a pressure gauge with a threaded hose, check the low side charge port for 0.93psi (about 1lbs). If it's below 0.40psi, you'll barely feel any coolness coming out of the HVAC system.

Wal*Mart and other auto stores sell re-charging kits along with the refrigerant too. The complete kit will have the pressure gauage with the threaded hose too.

As for the vaccum line check, remove the "dog-house" and look upward to the control head. You'll see the colored hoses running to the back of the knob. If you have a hand pressure pump, you can pump under 5psi to see if the line holds. And again, check the repair manual too. I'm only a Delphi Harrison engineer for GM HVAC control systems. Mostly the Dodge HVAC stuff is made by Behr or Valeo. The Dodge imports are mostly NipponDenso.

Stev

Thank you both for the replys. I'm going to check it out over the weekend.

seasharp,

Does that van have rear A/C as well? If so, open the mini-hood up front and read the lable for the proper charge on the HVAC enclosure. You can miss the big black label with white text on it.

Stev

Thanks Stev,

I found 2 issues. The reason for the cold to warm knob wasn't working right is that there is a plastic clip that hooks onto the metal rod that opens and closes the heater vent door. That had become detached when the door was about 1/2 way open, thus letting in a lot of warmer air. Also the A/C needed to be recharged as it was only at about .45 psi. After recharge and getting the vent door closed the A/C works great. Even have the family saying to turn it down becuase they are cold....hahaha. Thanks again!!