A/c stops working going uphill

ford
windstar
airconditioning

#1

A/c stops working when I am going uphill even if it a very slight uphill. No air comes from vents.


#2

You have a bad vacuum check valve. The check valve is there to make sure the vacuum to the vents is maintained when the engine vacuum drops, like when you accelerate up a hill.


#3

Bad vacuum check valve or a small vacuum leak somewhere in the climate control system. If you check, you’ll find that the missing air is coming out of the defrost outlets when this happens.


#4

On the 20-year-old car I recently sold, I would loose defrost air when driving uphill.

The check valve on that car was easy to spot - right on top of the intake manifold. Washing it with hot dish water every 6-8 years put it right.


#5

Right you are. I bought a used Olds Silhouette. The previous owners explained the A/C didn’t work, even though they had it charged like 6 times. I said, oh, it’s vacuum leak, I can fix that. They were stunned, I think a little upset the otherwise fine van still had A/C and no mechanic (probably dealer) helped them. And sure enough, and $11 part fixed it (was a leaking vacuum “master” switch - the selector was mechanical