Now the A/C is fully charged and pressure of system is normal. Normal A/C works fine. When i Switch over to Max A/C, works for a little bit, then air switches and starts blowing from the defrost vents under the windshield. Now my step dad says its a vaccum problem but im not sure where to even start troubleshooting. Any advice would be greatly appreciated. Thanks

 

here ya go

https://www.f150forum.com/f10/ac-max...defrost-51243/

 

&......

 

@Chelios... Thanks alot.. again.. I appreciate it. Imma go outside right now. Lol

@ymeski56... thanks for the layout. Appreciate it.

 

Take a look under the hood and you might find the schematic of the vacuum. It might look like this:



Disregard the questions and the check valve sketch. It was not a good solution. However, I did find leaks under the hood and fixed them. There might also be smaller leaks under the dashboard, but I think my AC is working well enough for now

You ought to look at the vacuum hoses. One of them is probably disintegrated. Pay particular attention where the hoses enter the little rubber boots/nipples where they enter into the plenums.

 

The AC is working amazingly great... thanks alot guys.

 

So what was the problem?

 

The little white tube that goes to the air box under the hood...