Hey guys I looked for the forum but couldn't find it. My issue is that when my A/C is in max setting and I accelerate the ventilation swithes to the defrost vents. It doesn't happen in normal setting just on the "max". I live in South Texas so this is a addressable issue since it's hotter than hell down here.

Thanks
Joe

 

We need some kind of information about your truck...

 

Sorry guys..... new at this. I have a 1995 f150 with a 5.0. All original equipment and the a/c is the r-134 system.

 

Moved to 1987 - 1996

 

Sounds like you have a vacuum leak somewhere

I replaced the cracked vacuum lines and that took care of almost all of the issue, the last thing I replaced was the check valve (I think that is what they call it). Once I replaced that it was all good.

 

Check all your plastic vacuum lines. I bet oney you have 1 or more lines that are cracked at a minimum.

 

Check the white (should be that color) vacuum line in the engine compartment near the firewall on the passenger side. My truck has a bundle up there where one white line loops back to an actuator that controls the airflow direction. That line is usually the problem.