Climate Control Problems

[scatter]

OK, it seems as if I have a climate control problem on my ’07 with the 6.0 engine.
Yes, I’ve read all of the previous posts on vacuum leaks related to heat, vent, and AC problems. I’m getting ready to seriously tear into the rig but was hoping for some specific insight from a few of you smart persons.

My problem seems a bit different than most.
1 – My blower works fine.
2 – When I switch to any of the functions, AC, vent, floor, mix, defrost nothing comes out of the selected area.
3 – If I turn off the blower and then back on again, the selected function usually works.
4 – If I change to a different selection it won’t work.
5 – Turning the blower off and then on again will usually get it working.

Now, all this started right after the rig came out of the shop for getting a new water pump, radiator, idler pulleys, belt, etc.
Coincidence?? I’ve checked everything I can find under the hood where they might have been working but can’t see any problem. And no, they didn’t have the dog house off.
So guys, any specific ideas before I have to get really serious trying to get into locations that one never wants to access?

[JWA]

It sounds as though the electrical part of the electro-vacuum switch aka Function Control used to select the different functions (Heat, Vent, Off, A/C, Defrost, Mix, etc) has failed. Perhaps the only real digging you need do is obtain an EVTM for your year chassis and troubleshoot the heater controls located in the center pod of the dashboard just above the radio opening.

Here's one in printed form: https://www.ebay.com/itm/16198622610....c101465.m3507

Work Shop Manuals covering different years are also available, these would be on DVD's and contain different user-selectable years and Ford models.

[scatter]

Thanks JWA. Yeah, I've got all the manuals so good to go there.
Just was hoping for something specific from someone that's gone there before. I'll check out what you suggested.

[scatter]

Well, a bit of good news. My problem is no longer intermittent!!
Now the only place any air comes out is through the defrosters.

From looking over your superb posts JWA, it appears that bypassing the vacuum reservoir might solve the problem.

On my '07 the under the hood vacuum hose that you show as being red is black. Gotta be the same thing though.

Just weird that this started right after all the work replacing the water pump and radiator. But, poo does happen….

So, time to order a few parts.

[JWA]

Before you start firing the "parts cannon" read this I authored a while ago over on FTE: https://www.ford-trucks.com/forums/1...-controls.html

Perhaps that will be helpful.

[posplayr]

Thanks JW, this is exactly what I needed. I was perusing the shop manual but it is fairly involved and you writeup should help get me oriented.

[scatter]

Yeah, I've been over that a couple of times JWA. That's what got me thinking that the vacuum reservoir might be the offending part.

I was thinking of by passing it by running a hose from the vacuum hose from the engine, where it comes out by the oil filler, down under the passenger foot well and cutting the black hose where comes out from the reservoir and putting it on to where it goes up to the vacuum solenoids.

If things start working that should nail down where the problem is. I realize that available vacuum will vary drastically depending on throttle position, engine load, etc. but if the problem is with the reservoir, things should start working a bit.

Thots???

[1der]

Just for clarity, for other readers : 6.0 is a diesel which requires a vacuum pump to generate vacuum as opposed to a gasoline engine which generates vacuum in the intake flow.

[scatter]

Yeah, my bad Ray. I put the variable vacuum bit in there for gassers without explaining the difference with diesels.

Us oil burners have a constant vacuum reading due to an engine driven pump.
Thanks for bringing it up.

[scatter]

Well, I ran a hose directly from the source to the line that goes to the dash solenoids as I mentioned above and everything works fine. I guess that shows that the problem is between the two places which pretty much ties it down to the reservoir and the few feet of hose.

So, I'll get a replacement reservoir and install it pretty much like JWA did.

Does anyone know if there's a check valve used on the diesels? Since we have a vacuum pump I wouldn't think one would be needed.