I found the black hose which runs through the firewall and put the vacuum pump on it. It is not holding any vacuum at all. I have partially disassembled the dash and center console, and found that the multicolored vacuum fitting from the climate control panel seems properly connected and sound. Where can I find the termination point where the black line connects to the "rainbow" vacuum cluster? Seems like it's somewhere up under the passenger airbag?

 

You can see a vacuum tubes quick disconnect behind the glove box. Empty the glove box then remove the two rubber stops; allow the glove box to hang down. See pics.


You can also see the recirculation air door with the glove box rolled down. See pic.


Hook up all disconnected vacuum tubes in the engine bay. Start the engine. While looking at the Recirc air door, select any mode except OFF or MAX AIR (Recirc) on the mode selector. You should see the Recirc air door close. Select OFF or MAX AIR and you should see the Recirc air door open. If this works okay the black vacuum source tube from the engine bay to the mode selector is intact. If the Recirc air door does not move there is a break in the vacuum source tube.


Rubber stops:



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Recirc air door:



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Vacuum tubes quick disconnect:



.

 

Ken,

I disconnected the 6-line quick connect and put the vacuum pump on the black hose that feeds to the selector panel.

With the selector at straight defrost (5), the black line did not hold vacuum, and I could hear air being sucked in from the back side of the selector panel. Does this indicate that there is a problem with the panel & if so, can it be fixed?

Also, with the engine running, I found that there was vacuum present on the engine side of the quick connect "rainbow" fitting, but only on the black line - measured about 13 psi.

What does this tell us?

 

Problem solved! It turns out that the control panel on the dash was bad.

I swapped in a new one from the salvage yard, and am in business. I was able to use one from a 99 Cherokee, but had to swap out the temperature control from my 98 (cable-driven) to replace the electronic one which came on the part from the 99. Everything else was a straight swap, and I'm happy to report that I now have ice cold air coming out of the correct areas.

Thanks to all who responded for your help!

 

Good work and thanks for the follow up.