I have been pouring over this forum, I have to say thanks to all of you. I parked this car out in one of the sheds thinking one day will have it back up and running. I like it, replaced the windshield, new brakes, tires, charged the AC, I found a vacuum line under the dash unhooked plugged it back in and now I can control the vents.
Only problem is heat blows out the bottom only so a blend door must be stuck. Will keep ya posted, Rod.

 

Hi Rod:
Glad to have you with us. Quick and dirty… You might want to take the passenger side knee bolster off and rap on the blower housing with a wrench or something. I successfully unstuck flaps this way on the '94 I used to own.

Cheers!
Scott

 

Hi Rod,

The technique Scott refers to of knocking on the blend flap motor housing with a screwdriver handle or something has worked for a lot of XJ40 owners. Short of removing the dash to remove deteriorated foam insulation crumbs that may be interfering with the blend flap operation, there are several other things you can do. Below are links to photos of work I recently performed on our '93. If knocking on the motor housing doesn't work, these photos should help you dig a little deeper. If you've never removed the knee bolsters or glove box, check my photo albums - I've documented those operations too.

Cheers,

Don

Welcome to Jag-lovers - Members Photo Viewing Page
Welcome to Jag-lovers - Members Photo Viewing Page
Welcome to Jag-lovers - Members Photo Viewing Page
Welcome to Jag-lovers - Members Photo Viewing Page
Welcome to Jag-lovers - Members Photo Viewing Page

 

Don, the pictures you share with us are amazing! I can control the vents, I just can't get heat up top to defrost the windshield. I can shut the defrost off and on but when I do the cold air blows out the center face vents. I wonder if the potentiometers are working properly.

 

Rod,

There are two demister flaps inside the dash that run on vacuum. IIRC, the vac line runs down to the passenger foot well area. If you're lucky, it simply have disconnected at the vacuum actuator. Bad news is you will have to move the center console back to properly access the actuator Or maybe the black tubing running from the actuator to the demist flaps have disconnected at one or the other flap(s), another words within the dash air box. You want to trace the black vacuum tube.

I've had something similar happen and had to remove the dash in order to properly repair. In my case the demister flaps loosened from the fasteners so air always blew up to the windscreen.

You could remove the center fascia and center vent, prop open the center flap and use a light to peer into the air box, but I doubt you will be able to see if the tubing is connected to the vacuum solenoid on each flap, you may only see the T-connector which splits the vacuum line between the two flap solenoids.

Other possibility is the demist flaps are stuck. Have you tried to gently push down on them from above? Don't use brute force, or you may dislodge the flaps from their fasteners.

Let's hope they're just stuck. If you can move them manually, but not with the use of the control unit, then you're faced with hunting down the disconnected vacuum line.

Replay to my private message and I'll send you an 18 page document that fully explains the HVAC system.

 

Tapped on the box some today, notice a little heat from the center vent and the side vents. Something did reposition it's self. I found a vac line under the battery box that was cheked. A small yellow line lower left side was in hooked as well.