Vacuum or blend door?

[jbgood]

Hi everyone. I have a 98 Ranger, 2.5L, 2WD,manualT. I have noticed now that the a/c max setting switches randomly from vent to defrost but runs fine at the a/c setting out the front vents. Had no problem all winter. Does this sound like a vacuum problem or control problem? Thank you.

 

[MAKG]

It sounds like the check valve in the vacuum system is not working. As in, it's not random, but rather changes when you stomp the throttle.

It's easily checked and easily replaced.

 

[jbgood]

Hi MAKG. Thanks for the info. I will check it out.