# Ford Mustang Air conditioner works when idle - doesn't when accelerating **URL:** \ **Category:** Maintenance/Repairs\ **Created:** [June 10, 2007, 6:59pm UTC](https://community.cartalk.com/t/ford-mustang-air-conditioner-works-when-idle-doesnt-when-accelerating/440 "2007-06-10T18:59:28Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![tomradi](https://avatars.discourse-cdn.com/v4/letter/t/8491ac/32.png) [@tomradi](https://community.cartalk.com/u/tomradi)\ **Post date:** [June 10, 2007, 6:59pm UTC](https://community.cartalk.com/t/ford-mustang-air-conditioner-works-when-idle-doesnt-when-accelerating/440/1 "2007-06-10T18:59:28Z")
93 Mustang Air works greeat when standing still. When I accelerate it diverts air flow from console to defrost vents and is not cool anymore. Any ideas appreciated. ---
**Author:** ![willey](https://avatars.discourse-cdn.com/v4/letter/w/a9adbd/32.png) [@willey](https://community.cartalk.com/u/willey)\ **Post date:** [June 10, 2007, 7:49pm UTC](https://community.cartalk.com/t/ford-mustang-air-conditioner-works-when-idle-doesnt-when-accelerating/440/2 "2007-06-10T19:49:49Z")
You have a vacuum leak. Check the vacuum canister under the hood for a leak. I believe it looks like a small coffee can on Fords. ---
**Author:** ![Cougar](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/cougar/32/21348_2.png) [@Cougar](https://community.cartalk.com/u/Cougar)\ **Post date:** [June 10, 2007, 8:54pm UTC](https://community.cartalk.com/t/ford-mustang-air-conditioner-works-when-idle-doesnt-when-accelerating/440/3 "2007-06-10T20:54:12Z")
Willey is correct. That is just what that cannister or resevoir is for. To keep the system from doing that when vacuum level is low, while accelerating. There may be a broken vacuum connection or bad restrictor valve. ---
**Author:** ![system](https://global.discourse-cdn.com/cartalk/original/3X/1/d/1d47c66a543aa6c5a7873bb2320858f978ff52ed.png) [@system](https://community.cartalk.com/u/system)\ **Post date:** [June 11, 2007, 4:27pm UTC](https://community.cartalk.com/t/ford-mustang-air-conditioner-works-when-idle-doesnt-when-accelerating/440/4 "2007-06-11T16:27:18Z")
There should be a check valve between the intake manifold and the vacuum plumbing for the vents. This check valve is there to prevent the problem you are having. Pull it out and test it. Make sure it faces the same direction when you put it back.