HVAC issue has me stumped

[Boomer453]

So I have the issue where I only have flow from the floor and defrost vents. I assumed it was a vaccum leak (even though the cruise control operates normally which I thought it wouldn't with a vaccum leak) and replaced the engine bay vac lines with a Mopar replacement. No change.
With the engine running I sprayed the vac lines with throttle body cleaner hoping to hear a change in idle if I hit a point where it got sucked into a bad spot in a vac line. No change noted.


I've pulled the dash cover to expose the climate controls, would spraying them with carb/throttle body cleaner produce a change in engine tone if there was a leak there?


Any other ideas?

 

[Link]

So I have the issue where I only have flow from the floor and defrost vents. I assumed it was a vaccum leak (even though the cruise control operates normally which I thought it wouldn't with a vaccum leak) and replaced the engine bay vac lines with a Mopar replacement. No change.
With the engine running I sprayed the vac lines with throttle body cleaner hoping to hear a change in idle if I hit a point where it got sucked into a bad spot in a vac line. No change noted.


I've pulled the dash cover to expose the climate controls, would spraying them with carb/throttle body cleaner produce a change in engine tone if there was a leak there?


Any other ideas?

Find the multi color vacuum line bundle behind the glove box and inspect it. Unplug it and verify it’s getting vacuum from the engine with the engine running.

 

[Boomer453]

I removed the glove box, I have vacuum all the way to the climate control box. I removed that harness from the glove box to the controller submerged it in water and put some air to it while plugging the other end-no leaks.

As per a different thread I put a finger over the black hose with the engine running then turned off the engine- it held vaccum until I uncovered it.

 

[Link]

What year? The HVAC boxes changed somewhere around 2002-2003 I think. Someone can correct the dates if I’ve got them wrong. I know my 2005 has a different box from a 1999 box.

Now you’re going to have to find each vacuum powered motor and inspect it. I think the motors that control where the air flows to are on the drivers side of the HVAC box. The motor that is on the right side is the fresh air/recirculate controls.

Are the dash controls working?

 

[Mac57]

So I have the issue where I only have flow from the floor and defrost vents.

Are you saying it only works on the one selector knob setting, the one with floor and defrost combined? Or can you also select just defrost, or just floor?

 

[Pantera99]

My '02 does this on occasion, I found a small vacuum line came off up under the passenger side front fender. Still does it sometimes on the highway when the wind comes from certain directions. Haven't looked behind the glove box before.

 

[MikeE024]

Maybe pressurize smoke test it if you can’t find the leak.

 

[Obi-Wan]

So I have the issue where I only have flow from the floor and defrost vents. I assumed it was a vaccum leak (even though the cruise control operates normally which I thought it wouldn't with a vaccum leak) and replaced the engine bay vac lines with a Mopar replacement. No change.
With the engine running I sprayed the vac lines with throttle body cleaner hoping to hear a change in idle if I hit a point where it got sucked into a bad spot in a vac line. No change noted.


I've pulled the dash cover to expose the climate controls, would spraying them with carb/throttle body cleaner produce a change in engine tone if there was a leak there?


Any other ideas?

Please fill in your profile including the year and any aftermarket modifications your Jeep has. It will help us all get you help way faster if we know what we're dealing with.

 

[Boomer453]

Sorry for not including vehicle info
2006 TJ X, 6 speed manual, 150k, original motor.
How do you access the HVAC motors and vac lines?

 

[Mac57]

You haven't found a vacuum leak, yet. Have you made sure the mode selector dial knob / switch is actually working? Sometimes the back of the selector knob splits open where it slides over the switch shaft. You spin the knob but it isn't gripping the switch shaft to actually turn the switch shaft. Pull the knob off. Then use pliers to turn the shaft on the switch itself. Any change?

 

[Boomer453]

Picked up a smoke machine and going try a pressurized smoke test today.

 

[Boomer453]

Did the smoke test. And I have a leak at the throttle body, seen here in the attached video. What exactly do I need to fix this? I think this is also the source of a high idle issue I'm having as well.