defrost mode only

[Tiberian]

Has anyone experienced this on their trucks? Mine just started blowing in defrost mode only (out the top vents directed at the windshield) no matter what selection I pick.

[dhanna6powerstroke]

Originally Posted by Tiberian

Has anyone experienced this on their trucks? Mine just started blowing in defrost mode only (out the top vents directed at the windshield) no matter what selection I pick.

Pretty common. You have a vacuum leak somewhere. Probably one of the lines going to the front hubs. Would check there first.

[ford_trck]

What if your truck is a gasser and 2 wheel drive and it only does it under load like going up a hill

[dhanna6powerstroke]

Originally Posted by ford_trck

What if your truck is a gasser and 2 wheel drive and it only does it under load like going up a hill

Still a vacuum leak. The engine is pulling the vacuum away when it gets under a load.

[Tiberian]

Thanks for the help. I've checked the vacuum lines around the pass. fender area and no issues that I can hear/see. I dropped the glove box and nothing.

How loud is the vacuum pump? I don't think I hear it running or starting up.

[dhanna6powerstroke]

Originally Posted by Tiberian

Thanks for the help. I've checked the vacuum lines around the pass. fender area and no issues that I can hear/see. I dropped the glove box and nothing.

How loud is the vacuum pump? I don't think I hear it running or starting up.

Not real loud. There is a vacuum line that connects to the motor on the fender. (It has to lines going into one connector). Remove the connector and let the air escape, reinstall connector. Turn key on and see if the pump comes on.

[Dave]

I agree its definately a vacuum leak somewhere. Check the lines going to the blend door themselves

[Tiberian]

Thanks. I stopped by Auto Zone to get a new vacuum pump just in case. The pump looks like it goes on the motor. If the pump is on the motor then what's on the pass. side fender?

[dhanna6powerstroke]

Originally Posted by Tiberian

Thanks. I stopped by Auto Zone to get a new vacuum pump just in case. The pump looks like it goes on the motor. If the pump is on the motor then what's on the pass. side fender?

The pump and the solenoid are both on the passenger side inner fender.

[Dave]

It could be in a different spot on a gasser. cant say for sure. I havent worked on one