pnolans

I've been having this problem for a while now. Have just been living with it.

If this has been asked and answered a million times, please forgive me.

My truck gave up the ghost this month and I'm back to driving my 98 XJ. I'm quite happy about it, but I have a bunch of stuff to fix. This is the most annoying currently.

I can only get air to blow from the defroster vents. The temperature and "air flow" ***** work on the climate control dash, but the vent selector does not. I bought another climate control board from U Pull and Pay a while back but never got around to doing anything with it. Also, I seem to remember reading somewhere about the vacuum canister under the bumper at some point in the past.

I suppose the next course of action should be to replace the climate control dash, and see if that helps.

If anyone has any additional suggestions, I would deeply appreciate it. Thanks in advance for any help,

Regards,

Pat

Turbo X_J

Vacuum lines old, rotted, leaky also check valve could be defective.

dzywicki

I just diagnosed this on my 99. Turned out to be a broken vacuum line under the hood. In my case, it was a small one that has a 180 degree loop in it to get from the main vacuum line to under the dash. The line is right by the firewall on the passenger side/middle. I used a heat shrink tube to reconnect the two sides and was good to go.

F1Addict

The most likely cause is the vacuum line mentioned by dzywicki which controls the blend door. It's a hard line that either rots or rubs on the AC expansion valve and wears a hole in the line. Without vacuum, the blend door defaults to defrost. It could also be the valve that controls the blend door but the more likely cause is that vacuum line.

In this thread I discuss my experience - there's a picture of the suspect vacuum line in the last post of the thread.

pnolans

I don't see a reference to a thread. I'm sorry if I'm missing something obvious.

Regards,

Pat

UPDATE: I Believe I found the thread that F1addict refers to

Could it be THIS one? https://www.cherokeeforum.com/f2/vacuum-mileage-235568/

EZEARL

See if this link helps:
https://www.cherokeeforum.com/f2/vac...4/#post3059123

pnolans

'Very good. Now I just need to get off of my butt and get out there and work on it!

EZEARL

Yep !!

pnolans

so, I spent some time with it today... I found 2 holes. There may be more. I need to go to town tomorrow to get some tubing. But I'm definitely on the right track. Thanks very much to all of you for your help!
I'll post the final result.


What a great forum!

Regards,

Pat

terlok

"Defrost" is the default setting. if something goes wrong you can still clear the windshield. I had the same problem on my 97 Cherokee. It was a faulty air gate under the dash. Not a DIY repair for the faint of heart or inexperienced. Entire under-dash HVAC system must be removed. Check console switches & vacuum integrity before jumping in.

pnolans

Absolutely! To both underlined statements. ESPECIALLY the last one!!!! I am still working on mine, and have found at least 2 breaks in the vacuum line. Will work more on that today.
But there could be more under the dash that needs to be done. I also have a "new" console from U Pull and Pay that I haven't tried to install yet, and may not need to.

One thing I will say about having to get in there: You DO learn a lot about your Jeep when you go digging around in there. And IMO that's always a good thing. But you will do a lot of hair-pulling and forehead-slapping!

Regards,

Pat

Joshua Blue

My 97 started to shift to the defrost when I get on the gas. After I'm done passing and let off the gas, the vents start to blow again. My question is where can I find the check valves or does anyone have a part number anywhere?

pnolans

FIXED! I got some tubing yesterday, and used some hose barbs to splice the breaks in the tube that runs to the canister.

Both my vent selector AND the cruise control now work.

Thanks for all the help!

Pat