OK, I need some help with this one.
My 2001 Dodge Ram 1500 can't seem to make up its mind whether it wants to blow cold or hot air out the vents, and it can't seem to decide which vent to use.
I'll turn on the A/C and it'll blow cool air out the dash vents for a few minutes then it'll switch and blow warm air out of either the defroster or the floor vents. A few minutes later it'll blow cold air out the floor, then it'll turn warm and switch vents again. I can hear the vent changing on its own and it's always random. The temperature here is in the 90's to 100's so the warm air may just be what's blowing in from outside, I can't be sure. It's an electrical control for this so I'm thinking a loose connection. I'm no expert with the environmental systems and really need some help troubleshooting this one.
Thanks guys,
Tim

 

I think its a vacuum issue. At WOT, my ram a/c cuts out and the air blows from the defrost vents. The defrost is the "default" vent that the climate goes to in the event of vacuum loss, safety thing. The thinking is "to hell with your piggies! the windshield needs to be clear!" As the vacuum rebuilds[slowly as it sounds in your case], the doors may change back to the floor vents as its passing through on the way to the dash vent position. I cant remember if it cuts the a/c clutch also at a WOT/low-vacuum situation. That would explain the hot air. So a vacuum issue seems to fit all the symptoms.

 

i second that.

 

I know this post is almost a month old but just in case you haven't figured it out yet I'll take a crack at it. Replace both vacuum check valves. There is one right off the passenger side of the intake and another one closer to the firewall. That should take care of it switching between floor and defrost when giving it gas. I worked as a mechanic for Chrysler, Dodge & Plymouth for about 10 years and that was a very common problem. Hope this helps.