Ac f-350


The heater/ac only blows out the defrost vent. What happened? What’s the fix?


Ford uses vacuum motors to control the flaps on the A/C. When the system leaks, or the vacuum is disconnected, the flaps default to defroster position.

You’ll need to check the vacuum line running to the A/C controls. If the vacuum is good, and not leaking at the lines, then the control must be leaking internally.


It’s a vacuum problem. More than likely a defective one-way valve (usually located in the engine compartment near the firewall and is in-line with a vacuum hose) or you have a vacuum pod leaking.
The pods look like small cans about 3" long.

They use 3 or 4 pods to operate the doors and considering the symptoms my guess is that a defective one would be located behind the glove box.
With the glove box removed operate the A/C,heater om various positions and note if the lever arms are being operated by the pods. If not, verify that vacuum is reaching the pod and if is then the pod diaphragm has probably ruptured.

There’s the possibility of it being a mode control problem but this is less likely.
Hope that helps.


This is a perfect example of how little you know about about automotive A/C and heating. The doors are controlled by vacuum actuators, if vacuum is lost then the syStem goes into default mode which is air coming out of the defroster vents.


Star… my post was removed before you answered my question so I’ll ask it again.

Please list exactly how many Ford trucks you have worked on?


STAR… why do you ignore my simple request? Is it because you have never worked on a Ford truck?