Air conditioning stuck on defrost

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shawnmiller21

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What's the box in behind/beside the glove box that has to do with the air conditioning? My AC is defaulting to defrost, I can't find a vacuum leak and someone told me to check that next. True or false?

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Defrost is the default setting for a vacuum leak in the system.

If you can not find any leaks / lines popped off, then I'd look at the blend door then.

First check here for any loose or disconnected vacuum lines:

intake vaccum.jpg



Then check here (inside bottom back side of passenger fender):

jeep vacumme line 001.jpg


jeep vacumme line 002.jpg



The second and third photo are of the vacuum reservoir.

This is how it is described by the FSM:

The vacuum reservoir is mounted to the rear of the right front inner fender wheelhouse in the engine compartment, under the battery tray. The battery and battery tray must be removed from the vehicle to access the vacuum reservoir for service. Engine vacuum is stored in the vacuum reservoir. The stored vacuum is used to operate the vacuum controlled vehicle accessories during periods of low engine vacuum such as when the vehicle is climbing a steep grade, or under other high engine load operating conditions.​
 
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I've already checked those, they're connected, not off or loose. That's why I'm moving on to the next option.

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Damn...But yes, I would check under the dash as best you can. Look for any ill-fitting or disconnected vacuum lines. It's got to be a vacuum line somewhere I suspect.
 
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That's what everyone tells me but I've found nothing so far. It's frustrating. Thanks for your suggestions though!

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Have you replaced your blower motor resistor by chance?

Is cruise control working or not?
 
Also, check the vacuum hose under the battery tray

It's not easy to see, you have to lay on the ground and look up into the engine compartment. The hose is under the battery tray. You'll see something like this:

1001267212_r3Tug-L.jpg
 
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Hmmm, you could take it to a shop with a smoke machine where they can fill the vacuum system with smoke, and it will leak out smoke wherever there's a vacuum leak. That's a sure fire way of figuring out if it's a vacuum leak (and where the culprit is).

It could be something like the blower motor resistor for sure, but I'm inclined to think there's a vacuum leak somewhere that is going unnoticed. A vacuum leak can often times be very, very hard to track down.
 
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Team Jeep, my 2002 Jeep Wrangler 4 cyl a/c is blowing cold air but is stuck on defrost. I suspect blend ac doors need replacement. Bought the book, no diagrams and no part found within nor does it show the location. Changed a/c switch and about to change the resistor. Autozone showed me the mode / blend air door part but where do I crawl under to replace before I purchase?
 
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