Jeep XJ Vacuum Line break

Air only blows out the defroster – repair.

My Jeep had the typical problem where the HVAC only blows out the Defroster. The defroster is the default mode when there is no vacuum supply. So I set about finding my vacuum leak.

XJ vacuum diagram HVAC

It did not take me long to find an obvious break in the plastic vacuum tubing. The trouble was, it was broken on the cabin side of the firewall. It was too far in to reach to make a splice.

I usd a bore scope to try to locate the broken end:

Not much hope of snagging that and pulling it through.

So I decided to approach from the other end. I pulled the climate control module out of the dash. I disconnected the vacuum harness and inspected the path the lines go through. Not much chance of fishing a new line through there.

So I decided to take the long way round. I pulled the two black lines back out of the conduit and found the Tee that connects them.

I used an old antenna to fish some vacuum tubing through the firewall and under the HVAC box.

I could not find a path up from the passenger floor so I went across under the console and up through the driver’s side.

I found the Tee fitting was the perfect fit for the tubing I had run.

I stuffed it all back in place and put the dash back together. Now I have control over where the air blows again. Now back to the task of making it blow cold air again.