A/C fades from body to feet on hills.

[geckolyn]

Please excuse this posting if this has already been asked, but could not find anything with a search.

1998 Explorer XLT V8. When driving with the A/C on, the air fades from the dash vents to the floor vents when going up hills. They don't have to be very big ones, but just a change elevation will do it. My thoughts are a blend door issue, but am I looking more at a vacuum issue?

Thank you,
Lyn

 

[drdoom]

Vacuum.

 

[geckolyn]

I thought so, but why all of a sudden would it do it. Any idea whats gone bad?

 

[Rick]

When you are on the throttle hard there is very little engine vacuum to control the vacuum servos. Check your hoses for deterioration. Check the elbow by the power brake booster and any caps on the vacuum tree on your intake manifold.

 

[drdoom]

If necessary check the lines going to the reservoir ball above the fender liner passenger side (if applicable).

 

[swshawaii]

^ Sounds like drdoom nailed it. Always accelerating when climbing hills. Sound familiar?

When driving with the A/C on, the air fades from the dash vents to the floor vents when going up hills.

• The ball has a check valve in it so that when you are accelerating enough vacuum remains so your ducts keep the air flow where you have set it.

http://www.explorerforum.com/forums/index.php?threads/what-is-this-thing-unit.429424/#post-3434602

Round plastic ball in right front wheel well??
http://www.explorerforum.com/forums...n-right-front-wheel-well.303406/#post-2623161