I was driving last night, and had the heat/ac turned off, and the vent set to inside air. I noticed that under acceleration that I started to get air coming in through the vents, as if I had it set to bring in air from the outside. It seems like there's a vacuum issue with the heater controls. Has anybody else noticed this? I also noticed the same thing with the a/c on. When I accelerate it opens the vent to the outside air.

I remember my dad had a similar issue with a '98 Ram that he had, and there was a tsb on it and he had to install a pill in a vauum line. In his case, if you had the blower on had it set for air to come out of the dash, it would change to the floor under acceleration. Seems like a similar problem.

Just wondering if anybody else has had this problem. I want to take care of it, because my a/c isn't cooling as well as I want it to, since it keeps bringing in warmer outside air every time I accelerate.

 

the Tempature controls are not opperated by vaccume lines on the neon, they are operated by cable simmilar to a throttle cable or a bicycle brake cable. if it is bringing in outside air, I would suspect it to be that one of the cables is bent, broken, or has came loose.
to check this place your forarms at 10 and 2 on the steering wheel and your hands on the guage cluster opening and push up should come off easly. careful though with age these pieces become somewhat brittle and can crack. you may also have to remove the passenger side part of the dash with a screwdriver. and then remove the black plastic piece for the vents with a little jerk. then you can see the cables mentioned above. turn the ***** and see if they operate.

 

The only two controls that use cables are the two center dials, the one for temperature, and the one that chooses which vents the air comes through.

The fan speed controls are electronic, and the switch farthest to the right that chooses if the air is circulated inside or if fresh air is brought in IS vacuum operated. This is what I was referring to in my original post. It acts as if you've turned this switch to the fresh air position under acceleration. There are two vac lines for it, a black one and a red one. They dial opens or closes a switch that either lets or doesn't let the vacuum go back to the mechanism that opens and closes that door.

I'm not sure at this point which postition(vacuum or no vacuum) corresponds to the door being open or closed. I guess I'll have to pull the controls and test the switch that the dial actuates. If vacuum opens the vent to outside air, then my bet is that the switch is leaking. If it's the other way around, then I'm thinking that I'm losing vacuum to that point under acceleration, causing it to open the door. It depends on how the operation is meant to work, which I don't know yet.

If anybody has some insight on this I'd appreciate it.