Troubleshooting HVAC controls

[bryancald]

Does anybody have vacuum diagrams for a diesel 240 HVAC system?
I can get heat/no heat with the temp slider.
What I can't do, is change where the air flows (it will only flow through the dash).
Now that it's winter, I need to defrost the windshield.

Is there a vacuum solenoid or something that fails routinely on these systems?

Thanks!

[nick]

I have a simlar problem with my 760, but in my case the air only blows out of the window defog vents. I can't get it to blow onto the passengers!

Sorry, I don't have any 240 vacuum diagrams. You should use www.ALLDATAdiy.com or AutoZone's "Mitchell"

I use ALLDATAdiy for my 760.

[casioqv]

It's a very simple system with just 3 mechanical vacuum switches which operate pneumatic servos- no electronics or anything. You probably just have a vacuum leak or disconnected line somewhere in the system, which you can trace via a handheld vacuum pump.

A cheap temporary fix if you find that one of your pneumatic servos leaks is to just cap off the line to it, and then everything else will start working again.