Spike

Hello and thanks in advance for your help.

My AC and heat blows fine but only through the defrost. It will not switch to the floor or front vents. I am not positive it is a symptom of the same problem but my cruise control is also not working. I am thinking my problem is with the vacuum system which controls both the cruise control and the HVAC.

I think the vacuum pump is under the front hood on the right side of the engine compartment?

What should I be looking for and how should I check it? Is there an electrical fuse for the vacuum pump? Could all this be caused by a vacuum leak anywhere in the system? How do I check the vacuum pump to determine if it is functioning?

Any help or clues to fixing my jeep would be greatly appreciated.

thanks again

OverlandZJ

There is no vacuum pump... not sure what your looking at but it may be the ABS pump.

The HVAC system draws it's vacuum from the engine. Your symptom is common and usually caused by a broken line leading to the vac cannister located on pass side inside the front bumper. Check this and the lines to it for a vac leak.

Good Luck, let us know what you find.

Howler_GT

X2 What Overland said.
There is NO vacuum pump.

There is a vacuum line that feeds the vacuum canister along the inner fender next to the battery. These lines are hard plastic and often times crack with age. Also, the canister itself breaks its mounting tabs and rolls around, thusly popping its connector.
I would start your Xj and crawl under the passenger's side of the bumper and feel for the canister and make sure the line is connected. If it is...pop it off and listen for vacuum leak.
IF you are getting vaccum to the canister then your problem lies elsewhere.

I am willing to bet you don't have any as you had stated your cruise doesn't work.
Do the same with the cruise control module on the driver's fenderwell. Pop the vacuum line off while the engine is running. You SHOULD have vacuum there. IF not...follow the line back to the motor...something is cracked/loose.