Fellas -

Air is only blowing through the defrost vents. No matter what I do - try to turn vents, A/C, heat, fresh air, recirculating, etc. Assume it's a switch or fuse issue somewhere.

Has this happened to anyone else? Any ideas on how to fix it?

Thanks,

Scott

 

you have a vacuum leak if you have shift on the fry find the vacuum valve that feeds the front hubs and plug the lines and see if that fixs the vents if so check the rubber lines on the hubs

 

it will have 2 vacuum lines and a elecrical plug on the trucks its by the vacuum pump on the fender

 

The ventilation/heat/AC system runs on vacuum. If there is insufficient vacuum, the system defaults through the defroster vents, as a safety measure.

Find the leak (or defective vacuum pump if you have a power stroke) and repair it. ESOF is a good place to start looking, but not always the cause.

 

Ok, I just replaced one of the front hubs and ESOF wasn't working afterwards. I'm planning on swapping to Warn hubs. Can I just remove the flexible vacuum lines and put a plug over the opening on the hard line?

Thanks,

Scott

 

Yes, but that might not solve the issue.

 

Yes you can. There are other vacuum lines under the dash on the passenger side. Check those as well...they go to the control panel for the climate control system.

 

Ok, fellas. Put new Warn hubs on it, which I've been wanting to do for a while (took all of 20 minutes). Then I plugged the vacuum lines where they enter the wheelwells. Still no vacuum.

That's the vacuum control solenoid on the passenger side of the engine compartment, behind the battery, right? Is there also a vacuum pump? Any tips on how to diagnose from here?

Thanks

Scott

 

You should hear the vacuum pump running turn the key own but do not start it and you should hear it if not your vacuum pump maybe bad or blown fuse

 

Try plugging the to vacuum lines at the vacuum valve for the 4 wheel drive the vacuum valve maybe leaking

 

Greets, so I was having the same problem air not coming through center vents. In troubleshooting the vacuum system it appears the valve just behind the battery is bad- what does this control?

If I take the vacuum line off and plug the line going to the reservoir and cab my center vents work. The other line is for the front hubs? I tested that line and it is fine no leaks. For now I have a golf tee plugging the vacuum line that I took off the valve. What is this part called- is it the EGR vacuum valve?

 

I had to fix this issue on my truck back in Feb, I don't remember the actual name but i think it is something like "ESOF Vaccume Switch" or something like that. With mine the AC/Blower would work fine untill i tried to switch to 4wd, then defrosters, Checked hub lines and they were fine, then I was told that that switch was sorta known to go out and it only cost about $20.00 so I figured what the heck, Called the ford dealer (after napa, AutoZone, Advanced Auto all to no luck) and ~$80.00 later the issue was fixed.
Until I got it fixed I just plugged the line that went to the solenoid thing, Just had to flip the hubs manually if I wanted to use 4wd.