# AC Doesn't Work When Engine is warm

**URL:** <https://community.cartalk.com/t/ac-doesnt-work-when-engine-is-warm/49605>\
**Category:** Maintenance/Repairs\
**Tags:** volvo, s40\
**Created:** [May 30, 2010, 5:17pm UTC](https://community.cartalk.com/t/ac-doesnt-work-when-engine-is-warm/49605 "2010-05-30T17:17:30Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Chewka](https://avatars.discourse-cdn.com/v4/letter/c/7c8e57/32.png) [@Chewka](https://community.cartalk.com/u/Chewka)\
**Post date:** [May 30, 2010, 5:17pm UTC](https://community.cartalk.com/t/ac-doesnt-work-when-engine-is-warm/49605/1 "2010-05-30T17:17:30Z")

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The AC works fine for about 10 or 15 minutes. Then it starts blowing warm air. There is also a very brief smell of something weird. AC won’t blow warm air until the engine has cooled off.

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**Author:** ![tardis](https://avatars.discourse-cdn.com/v4/letter/t/f0a364/32.png) [@tardis](https://community.cartalk.com/u/tardis)\
**Post date:** [May 30, 2010, 7:33pm UTC](https://community.cartalk.com/t/ac-doesnt-work-when-engine-is-warm/49605/2 "2010-05-30T19:33:36Z")

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You may have a heater control valve or blend-air door problem. There’s no way to say for sure without someone doing some diagnostic tests.