Engine/Transmission (1998.5 - 2002) A/C vent controls

[Rockcrusher]

No matter which mode I put the control knob in, air only comes out defrost vents.

I checked vacuum and am pulling 10 inches with my old vac guage. Checked all the vacuum lines and everything seems to be OK. A/C comes on OK, fan works OK.

Suspect bad control modual?

Hard to tell if control is electrical or vacuum. I have the service manual, but discription not too clear.

Looks like a nightmare to check doors etc.

Dealer could not fix sticking blend door before, so dont want to take it to them if at all avoidable.

HELP!

 

[kstehnacs]

Sounds like vacuum problem. Blend door is electrical actuator. Floor/defrost and panel/defrost are vac. operated. If you have good vac supply to the control head, then either the control is bad or the door is not moving(broken or stuck in the box). This is common in durangos, havent seen it in fullsize trucks though. Hope this helps, Kevin.

 

[B.G. Smith]

As stated aabove. 10" vac. is probably not enough. The test for the pump calls far a minimum of 25". Try to check it at the pump or run a hose to a gasser manifold, should get around 18" there. bg

 

[Rockcrusher]

Thanks for the replies.

Funny thing, today it is working fine. Weird.

Will retest the vacuum at pump with better gauge.