a/c question

[buck96]

96 bronco, A/C redirects to defrost and floor vents when accelerating and all the time in Max air, I know it's a vacuum issue and have found only one valve/vacuum part in parts manuals for it so I figure that must be it. Does anybody have any idea where this valve/vacuum is located and the best way to go about changing it? I can't find any info on how to do the repair.

[Davescort97]

Welcome to AF!

The blend door actuator is vacuum controlled. If you have a vacuum leak the door defaults to the defroster setting. Set the A/C on a normal setting with the air coming out of the dash vents. Starting at the vacuum source pinch off the hoses one at a time. When the A/C goes to the defroster vents this is the line you want to trace for leaks. If a vacuum hose was off completely the A/C would go through the defroster vents all the time. Because the A/C goes to the default under acceleration is an indicator that maybe the vacuum canister is leaking. It is supposed to hold enough vacuum to operate the system under a load. In addition it could be a leaky hose or a hole in the vacuum motor diaphragm.

[buck96]

Thank you Davescort97, I'll start tearing into it today until it gets to hot to work on it, no shade tree for this (not so) mechanic -al.