Hello.. I have a 98 Durango 5.2 4x4 and this is my third post of the night. After I installed a new heater core, the air would come through the front vents for a while but on and off it would come through and not come through.... I never had the problem before so I don't think the check valves are bad. Is it possible it is just loose under the dash somewhere?

 

sounds to me like you have an intermittent vacuum leak going into the dash somewhere, the directional and temperature vents are vacuum actuated on your truck

 

I would guess the blower motor connector could have gotten knocked loose while you were in the dash. Other than that, I also agree with shrp that you could have an intermittent vacuum leak.

 

So you pulled the dash and replaced the core right?

Opposed to my partners above who very well may be correct, I'm leaning towards mechanical failures due to faulty reinstallation of the parts in and around the core's air box.

Check the blend door and the pivot points. May or may not be able to do so without pulling that side of the dash again.

If it is indeed stopping due to loss of power to the blower, check connections as advised.

IndyDurango

 

Yeah thats what I've been thinking about a loose connection... It was intermitent and eventually just stopped and when I go down a bumpy road, I can hear that door jiggling. I'll crawl into the floor and see if I can find that one hose that plugs in on the driver side of the box assembly, maybe that came loose cause I did check that door and pivot points before I put it back in. I'll let you know what I find