Heater control problems, 2004 F350

[Rancher Ed]

Right now on our 2004 F350 6.0 diesel w/auto the heater control is not working right. The temp part works fine, the get nice hot air when you turn it to hot, and cold air when you turn it to cold, and the fan works fine on all four settings. The problem is the knob that controls where the air goes, be it defrost, feet, or the vents that point at you. When you turn it to off, it is off like it should be, but when you turn it on, no matter where you turn it, feet, vents, both, or defrost, the air only comes out the defrost.

Because the defrost works, we don't have to have it fixed right away, but I am wondering if any of you guys know what the problem might be? I turns off when it should, and the heat and fan work great, you just can't pick where the air comes out, it always comes out the defrost no matter what you select.

Ed

 

[56FordGuy]

Sounds like a vacuum problem. Is it 4wd? The lines down to the hubs are bad about leaking.

 

[Diamondpilot]

Yep, never had the issue personally but know others that have. Sounds like a vacuum leak. Like mentioned before the lines going to the front hubs on 4x4 trucks would be the first place I looked.

Chris

 

[Dmace]

Since your truck is diesel there is no natural vacuum like a gas engine. This means there is a separate vacuum pump for stuff like the hvac controls, auto hubs, cruise control, etc...
If none of these are working then its probably a bad pump, if only one is not working then either the switch for the hvac controls is not working or a leak in the vacuum lines to the controller.
http://www.ford-trucks.com/forums/990270-2004-6-liter-diesel-vacuum-pump-question.html

 

[Rancher Ed]

Interesting. Yes it is 4WD, and the auto hubs don't work right now, you have to manually lock them in for the front tires to drive. I'm not sure but I think they both quit working about the same time. I am pretty sure the cruise control does work, but I am not positive about that.

Sounds like there is definitely a problem somewhere with the vacuum, so that is a good place to start. Thank you very much.

Ed

 

[sparc]

Since your truck is diesel there is no natural vacuum like a gas engine. This means there is a separate vacuum pump for stuff like the hvac controls, auto hubs, cruise control, etc...
If none of these are working then its probably a bad pump, if only one is not working then either the switch for the hvac controls is not working or a leak in the vacuum lines to the controller.
2004, 6 liter diesel, vacuum pump question - Ford Truck Enthusiasts Forums

I would check the power to the pump before I jumped on the bad pump theory right away. Could be a bad wiring connection or blown fuse to the pump. Verify power to the pump before you replace it.

 

[automech]

The HVAC vacuum pump is located under the hood on the right fender well near the firewall if you want to look at it.

 

[ttstpsvernon]

I had a 99 f 250 and the vent door was operated by an electric motor i don't know if the 04 f350 is the same. also i have an 04 and 05 e-450 with the 6.0 L diesel and they have vacuum pumps driven by the poly v belt but have never had to work on the heater vents on them

 

[Rancher Ed]

Sorry it has been so long, I have been pretty busy. Anyway, it turned out it was the vacuum pump that wasn't working. All the lines were good, and once the pump (which is electric, not belt driven, just FYI) was replaced everything works like it should.

Ed