So when my ac is on it mostly comes out the dash vents but some comes out of the defrost vents. Like 70-30 I guess. If I am not mistaken it is all controlled by vacuum. Any suggestions?

 

You are correct, i would check for vacuum leaks.
The nice thing is, the climate control and hubs are ALL that is vacuum controlled. My F150 had a vacuum leak that made it run like junk, took me months to find.

I hear the hub lines are a common spot for the leaks.

 

The vacuum canister is on the passenger firewall behind the battery. Thats a good place to start.

Chuck

 

You could try this little adjustment on the vacuum pump. I have yet to try it on mine. If that doesn't work, the pumps are relatively inexpensive to replace.

This is assuming you don't have a vacuum leak anywhere else.

 

Also, the little valve on the passenger side near the firewall behind the oil fill cap. It's black and a little bigger than a golf ball. The hose fell off of it on my truck and caused the same symptom. Easy fix. Just find the hose and reconnect it to the valve.

Search for this thread, it is helpful too. 'AC blows out Defrost'

This thread: https://www.ford-trucks.com/forums/1...=blows+Defrost

 

Thanks for the reply's I will try and check this all out over the weekend.

 

^definitely check the vacuum pump, there was a tsb for it being inoperative or running continuously. I had to replace mine

 

I have some diagrams if it will help.




AC 1




AC 2 Valve




AC 3 EATC


What I don't have is the 4X4 diagram. I'll try and get that up for you later.

Sean

EDIT : Got the Service info from the workbook for you. One nice PDF for you.

 

Would this diagram work for a 04?

 

Some things will be the same. But not all.
I no longer have a 2003~2004 to look at.

Sean

 

Here, run through these tests methodically.

 

Found my problem was a bad alternator. Wouldn’t keep ac clutch engaged.

 

Old thread back from the dead but good information!
If your vacuum lines have a leak anywhere or your truck has ESOF 4wd and the hub seal or seals are compromised you will also not build vacuum and the hubs won’t engage and the vents will default to the defrost mode. I deleted my vacuum lines to the hubs and installed manual Warn hubs.

 

The same problem of AC only coming out the defrost vent started for me today. Followed the ideas in this thread and found what appears to be a snapped vacumn line in the engine bay.

https://ibb.co/R0Y57Bv

What is the easiest fix here? Is there a two ended nipple connector that I could just use to reconnect the line?

Anyone know the part number?