Gentlemen, I'm helping a buddy with a 2000 F350. We are here in Florida with a low temperature of 65 and a high of 95.

The blend door on this rig has failed. The actuator motor is not working, for whatever reasons.

I spent a few hours with checking the electrical system. There's been some monkey business in the past, but the fuses look good for the blend door actuator.

I tried to turn the blend door from the actuator rod insert with a short screw driver as well as the D slot rod on the actuator and no avail. Nothing. It's good ad not moving.

I would like to rig the truck to MAX AC where it blows out the vents. We need nothing else here. Right now it is to the default of the windshield defrost. With MAX AC, I'm fairly sure I get defrost, feet and VENTS.

I'm able to lift the one lever behind the glove box and get it to feet, but not vents.

How do I get all the dash vents to open and stay open? I'm happy to cut whatever open and remove things. Be nice to do this with a bit of time and not money or parts.

 

Sounds like there is some confusion.

The blend door and its electric motor are ONLY for temperature control. It only controls outlet air temperature and has nothing to do with inlet or outlet airflow selection. The quickest way to override it for A/C only is to go under the hood and clamp off a heater hose.

Inlet and outlet door selection is vacuum operated. If you loose the vacuum supply, the system automatically defaults to defrost and fresh air. Suggest looking at the vacuum supply to the HVAC control head first and not hacking things up.

If its a diesel, start by checking to see if the electric vacuum pump works. It it's a 4x4, check the PVH solenoid for a cracked body. Otherwise, check the vacuum supply hoses near the battery for damage or leaks. That will get you started.

 

Thank you Project. Yes a bit of confusion, but I'm close!

Turns out the vacuum line into the cab was broken. I repaired it. The volume of suction seemed fair, but there could be additional leaks as I could not test pressure.

There still is no change in the outlet door flow. The plastic dash dash cover over the control panel is very tired and cracked. I inspected the lines going to the selection switch and they look good.

I'll look again, but there's not a lot of visual inspection ability as the wires are fairly dirty and everything is sticky from being old vinyl tubing in Florida.

I'm not sure I'm getting enough vacuum pressure to start with. Suggestions? And thank you again!

 

Get a hand vacuum pump. You can use it to both measure vacuum or use the hand pump to make a vacuum to test for leaks or to test vacuum-actuated motors. Really handy for troubleshooting vacuum issues.

 

Huh. That's good advice. I'm not sure why I could not figure that out.

What kind of pressure am I looking for from the tube coming into the cab?

 

It seems as the only failure is low vacuum pressure or the switch has failed?

I don't understand how the tiny bit of vacuum pressure can actuate that heavy defrost door...