My 95 f150 xlt has a promblem I've never heard of..when I turn on the the ac on vent while driving it only blows out at the defrost vent but when I hit the brakes/slow down the air comes out the main vents like it should...anyone heard of this or any suggestions?

 

I believe it's a vacuum problem. I've seen it before on the forum, a search will bring it up.

 

That's right. The default with no vacuum is defrost. If you have a leak when the engine is under load the vacuum falls and the spring takes over.

 

Check the white vacuum tube on top of the heater box under the hood that goes to a vacuum motor they are notorious about going bad

 

If my ac worked at all I'm bettin I would have the same problem. I was re-wiring a light under my hood, bumped that line and part of it disintegrated.

 

You should repair or cap that line. Its leaking unmetered air into your intake. It is likely costing you power and mpg

 

Didn't know that, thanks. I'll take care of it in the mornin.