Strange Vacuum problem.

My air conditioner/heater is coming out of the defrost vents which leads me to believe that I have a vacuum leak somewhere. I have gone over the tubing under the hood and everything looked good to me. I checked the infamous section under the battery and everything.

The thing that makes it weird is that my 4 wheel drive works flawlessly, and my engine is running just fine. I am even getting 22 MPG with 31’s. The Jeep hasn’t run this smooth for years. It all started when I changed the gasket on my header/intake months ago. I first noticed that I had two of the lines on the manifold backwards. (the one to the map sensor and the one next to it were reversed) I thought I had solved the problem but still no AC.

It’s starting to get a little cold and I need to get this figured out before I start to freeze my @ss off!

What else could it be? A bad MAP sensor wouldn’t cause this problem right? I haven’t messed with the radio or anything like that for a while either. I am stumped.


Thanks for any help,
Michael

91 Cherokee lifted 3 inches. Rubicon arms and track bar. Borla header, catco cat, flowmaster muffler.

There is a small tube that goes thru the firewall near where the A/C lines go thru.... This is the vacuum line for the climate controls.... Check to see if you have vacuum at that point. IF you have vacuum then you will need to go under the dash looking for a vacuum leak to the climate control damper actuator.
Since this started after removing the intake manifold... then I would check the main line feeding the vacuum to the small vacuum line.... Ensure it is not obstructed....

Charles