Air symptom - vent or AC
 

Hey all,

2001 360 4X4 Quad

I don't think this is a wild vents problem. I've read and heard for years that when an AC is on, the compressor kicks on and off. I don't dispute that, but I've never noticed it when inside the vehicle. (Maybe you're not supposed to.)

Anyway recently, I've noticed that while driving with the AC, there will be a brief second where the air comes out moist and warmer than it's supposed to, then goes back to normal. It does this every few minutes. I figured it was the AC kicking on and off and I was just now beginning to notice it. I haven't worried too much about it because the AC works great. I thought it might be getting low on freon or something and I just hadn't got around to checking it yet.

But today, I noticed the same symptom while driving with just the vent on. It was a bit cooler than usual this morning, and I just like to have air flow while I'm driving. With the thermostat set all the way to cold, all of a sudden, a blast of warm, moist air came out, then it went back to normal. It did this every few minutes or so, just like when the AC is on. Now I'm thinking it has nothing to do with the AC itself.

What am I looking at here?

As a general rule;
Wild vents cycle with intake vacuum loss.
Errant A/C compressor cycling will be low refrigerant, or faulty pressure switch.

Thanks, Spillage. So, my first step is to check refrigerant for the AC. Any ideas on why this would happen with only the vent air on? The two seem to be linked since the symptoms are the same.

The A/C is on all the time, just as the heat is on all the time... what you get from the vents depends on the mixer/blender door position.
Even with full heat, the A/C is pulling humidity from the air.

Wonder if his blend door is flopping loose on the the coupler for the motor that controls it.

Stripped coupler can be an issue, but I don't know it would cycle if the coupler is shot.

Thanks for talking this out, guys. Let me guess - this is something that is only accessible via ripping the whole dashboard out, right? LOL If that's the case, I'll just let it go until everything stops working altogether. If not, I might be able to check it out with some light guidance.

I'm probably not going to mess with even checking the refrigerant - the AC is plenty cold 99.9 percent of the time. I can tell when it's low because I've charged it before. It seems like this newer stuff they use can't take as much loss as the old stuff before the air becomes useless.

If you're on vent (not using the A/C), the evaporator will get cold and the compressor will cut out to avoid freezing it up... this cycling will happen less often when air is passing over the evaporator (using A/C).

Thanks. Is there a diagram somewhere that I can look at so I can find out where this door is and check it out? I suppose I can just start digging, but it sounds like you might already know right where it is :)

Look at the FSM in the FAQ/DIY forum.
https://dodgeforum.com/forum/2nd-gen...e-manuals.html


(Google is your friend)
This is the generic layout.
http://ww2.justanswer.com/uploads/RJ...923_inside.GIF

This is where it lives
http://i166.photobucket.com/albums/u...y/IMG_3324.jpg

This is the guts
http://i51.tinypic.com/2lvirzp.jpg


Reading your original post again, I would personally be looking for a vacuum leak... My call is you have early signs of the classic wild vent issue.
Do the fault finding and isolate the real issue, before you start tearing the dash apart.