HVAC

Vacuum leak

chast wrote:
Hi all--our '97 Dodge 170P has a glitch. Crazy weather here in the Pocono Mts. of Penna. has us using both the heat and the AC at times. Unit has started sending all output through the defroster vents instead of where you want it. Both systems work fine, it just sends everything out of the defroster vents. What gives and where do I start?

X 2

Our '98 Dodge Xplorer had exactly the same problem. It would especially do this when going up hills where the engine had to work harder. It would sometimes shift back and forth from dash to defrost vents as you went up and down grades in rolling countryside.

We were able to get it fixed and I don't recall exactly what was done. I believe it had something to do with vacuum, as mentioned, but not just repairing a leak. I think there was a valve or switch that was replaced.

If I can find out I will respond again. It was annoying, but has worked fine after the repair.

David

Edit: removed an extra word

When the HVAC system has a leak in the vacuum system that moves the blend doors, it almost always defaults to the defroster vents for safety reasons. At least your defroster will work until you get the thing fixed.

Had the same thing happen on my 93 Dodge. Turned out to be my Sirius radio receiver that was installed behind the regular radio had shifted and crimped the vacuum line to an actuator. That vacuum actuator is located just behind the radio and I removed the radio to see it.

Just a thought.
Dave 04 Excel TD

Thanks all for the responses. As you predicted, I was able to find a broken vacuum line and all is well. Thanks again for the support!