# Air conditioning/heating/ventilation system

**URL:** <https://community.cartalk.com/t/air-conditioning-heating-ventilation-system/45812>\
**Category:** Maintenance/Repairs\
**Tags:** toyota, highlander\
**Created:** [March 9, 2010, 6:21pm UTC](https://community.cartalk.com/t/air-conditioning-heating-ventilation-system/45812 "2010-03-09T18:21:47Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![heplo5615](https://avatars.discourse-cdn.com/v4/letter/h/eb9ed0/32.png) [@heplo5615](https://community.cartalk.com/u/heplo5615)\
**Post date:** [March 9, 2010, 6:21pm UTC](https://community.cartalk.com/t/air-conditioning-heating-ventilation-system/45812/1 "2010-03-09T18:21:47Z")

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on occasion hot air would blow out from the vents when the a/c is on; I would either turn the fan off/on and/or the a/c control button and the problem would go away. Also: one cool evening I had the fan on with circulation from the outside air coming in. Amazingly, after a few momutes very hot air started coming out from the vents. This leads me to believe the problem is not necessarily with the a/c system, but elsewhere. Any ideas? Thanks.

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**Author:** ![Joseph\_E\_Meehan](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/joseph_e_meehan/32/21_2.png) [@Joseph\_E\_Meehan](https://community.cartalk.com/u/Joseph_E_Meehan)\
**Post date:** [March 9, 2010, 7:40pm UTC](https://community.cartalk.com/t/air-conditioning-heating-ventilation-system/45812/2 "2010-03-09T19:40:13Z")

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Did you have defrost on? I would start by looking for a vacuum problem, unless your Highlander uses cable controls for that system.