Only getting HVAC air to the defrost and feet vents

Hashmeir

Hashmeir

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Joined
Oct 25, 2020
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Texas
Having a little problem with my heat and air. Currently only getting airflow to the defrost vents and feet. Any clue what would be causing this? Also when on heat i only get 3-4 seconds of good heat then it goes back to cold. Any feedback would be much appreciated.

Jeep Enthusiast here and a slight amateur mechanic here and hoping to do as much on my own as I can. Just swapped out a new head gasket and about to tackle the main seal soon.
 
Do you have cruise control ? IF so... do you have any problems with its operation ?
You should check the vacuum lines in the engine compartment (intake manifold, evap emissions, cruise control), the vacuum reservoir connections (pass side beneath the battery) and the lines going thru the firewall that tie into the climate controls. Check the operation of the blend door actuator and the climate control mode selector switch.

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Same thing happened to me on TWO TJs. Each time it was a vacuum leak. I would bet money that is your issue.

They can be tough to spot though, so often times you'll need to build (or buy) a smoke machine.
 
CharlesHS said:
Do you have cruise control ? IF so... do you have any problems with its operation ?
You should check the vacuum lines in the engine compartment (intake manifold, evap emissions, cruise control), the vacuum reservoir connections (pass side beneath the battery) and the lines going thru the firewall that tie into the climate controls. Check the operation of the blend door actuator and the climate control mode selector switch.

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Yes I do. I checked the cruise control the other day and seemed to be working fine. My first thought was the blend door and checked to see if there was any movement when the settings were changed. Looked like it was in worjing order and would move when changed. Looks like my next step is checking the vacuum lines. Thanks for the feedback
 
Chris said:
Same thing happened to me on TWO TJs. Each time it was a vacuum leak. I would bet money that is your issue.

They can be tough to spot though, so often times you'll need to build (or buy) a smoke machine.
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I have also seen a soap and water method used. Is smoke the easiest to spot?
 
So I finally got around to finding the leak and I think I found the culprit. Y’all were right and it was the one under the battery. Now the question is to how to fix it. Will I need to buy a whole new harness or will I be able to fix the elbow?

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Hashmeir said:
So I finally got around to finding the leak and I think I found the culprit. Y’all were right and it was the one under the battery. Now the question is to how to fix it. Will I need to buy a whole new harness or will I be able to fix the elbow?

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You should be able to rig something up as a means of fixing that elbow, even if it's just another piece of hose that slides over the hard line.
 
Just go to Napa or any auto parts store & get some bulk vacuum line with that same inner diameter.
 
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