Diesel HVAC controls, pls help

[DieselWarrior]

I know diesels dont generate vacuum and I know most HVAC controls use vacuum to actuate dampers, etc..

When I slide mine to defrost, it doesnt work. Come this winter, Im going to want some hot air on the windshield at some point, so I figure I better fix it before then.

So before I get too involved, can someone give me the run down on how it works?


Thanks,
Andrew

 

[Fordum]

I'm betting someone here can. I know that a lot of diesels have vacuum pumps on the engine just for that purpose.
Its easier to add a pump for the trucks that have diesels than to build an entirely different control system from the gas engines.
Did yours ever have a vacuum pump?
Also, look around the heater core housing under the hood, or under the dash and see if you can find an actuator.
Any one of them would do.
If it has an electric wire going to it, then its not vacuum. But, if you see the little rubber hose, then you are going to have to find a vacuum source.

Someone else who actually knows will chime in here after a while, but that gives you something to do in the meantime

 

[tRustyK5]

If your truck has AC it'll have the vacuum controls. If it didn't come with AC it'll have cable controls.

The most common culprit is the blend door plastic tab. It breaks, and the blend door stays open making defrost very weak. If you have the vac controls, there is a vac manifold for all the little lines which could be unplugged. Getting to it requires removing the dash bezel, and heater controls. You might be able to get to it from underneath, but you know how uncomfortable and awkward that can be.

Rene

 

[DieselWarrior]

Damn Rene, your a walking GM repair manual!

Thanks, Ill take a look. If I can finger out how, Id switch all the dampers to solenoid actuators.

Ill see about pulling some stuff to gain physical and visual access to the oh-so-joyous plumbing and get back with you.

I hope tomorrow Ill be able to do my XJ steering shaft swap... I just left Harbor Freight, the bolt has a SPLINE head, I bought a set of SPLINE SOCKETS in SAE (they come in metric too) to get the lower bolt thats on the steering box.

Thanks for EVERYONES help! My truck has quickly become a joy to drive thanks to all the advice Ive been able to get here! I only hope that my videos both encourage someone and give enough instruction to help someone else in there 4X4 repairs, build and mods.

I realize that my setup is light compared to a lot of the trucks here, but its been a LOT OF WORK just to get her this far, and Im proud of her.

Yesterday I asked my daughter if she liked the truck, she does... but she said she wished it was finished on the paint job, so today I painted until I ran out of paint, I only have a small patch on the roof to do and that is all done.

Cheers,
Andrew