# 1999 Ford E150 - HVAC issue

**URL:** <https://community.cartalk.com/t/1999-ford-e150-hvac-issue/175536>\
**Category:** Maintenance/Repairs\
**Tags:** ford\
**Created:** [March 4, 2021, 8:55pm UTC](https://community.cartalk.com/t/1999-ford-e150-hvac-issue/175536 "2021-03-04T20:55:49Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![webvidman](https://avatars.discourse-cdn.com/v4/letter/w/46a35a/32.png) [@webvidman](https://community.cartalk.com/u/webvidman)\
**Post date:** [March 4, 2021, 8:55pm UTC](https://community.cartalk.com/t/1999-ford-e150-hvac-issue/175536/1 "2021-03-04T20:55:49Z")

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heater/defrost won’t switch from defrost to heat

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**Author:** ![Purebred](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/purebred/32/46796_2.png) [@Purebred](https://community.cartalk.com/u/Purebred)\
**Post date:** [March 4, 2021, 11:59pm UTC](https://community.cartalk.com/t/1999-ford-e150-hvac-issue/175536/2 "2021-03-04T23:59:10Z")

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Failed actuator.

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**Author:** ![Nevada\_545](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/nevada_545/32/41232_2.png) [@Nevada\_545](https://community.cartalk.com/u/Nevada_545)\
**Post date:** [March 5, 2021, 12:27am UTC](https://community.cartalk.com/t/1999-ford-e150-hvac-issue/175536/3 "2021-03-05T00:27:37Z")

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Check the vacuum supply line from the intake manifold to the vacuum reservoir and firewall. If there is no vacuum to the control panel the system will remain on defrost.

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**Author:** ![weekend-warrior](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/weekend-warrior/32/26122_2.png) [@weekend-warrior](https://community.cartalk.com/u/weekend-warrior)\
**Post date:** [March 5, 2021, 12:58am UTC](https://community.cartalk.com/t/1999-ford-e150-hvac-issue/175536/4 "2021-03-05T00:58:52Z")

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also it could be the switch itself. my son has the same problem in his ford work van. when it happens he changes it and it goes back to normal

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**Author:** ![ok4450](https://avatars.discourse-cdn.com/v4/letter/o/e9bcb4/32.png) [@ok4450](https://community.cartalk.com/u/ok4450)\
**Post date:** [March 5, 2021, 2:41am UTC](https://community.cartalk.com/t/1999-ford-e150-hvac-issue/175536/5 "2021-03-05T02:41:55Z")

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I assume this truck has an EATC panel? If so, vacuum leaks inside the EATC are a common problem due to a number of O-rings, etc which have a tendency to fail with age. Stuck on DEF is the main issue but there are others.

There are internet and YouTube guides and tutorials on doing this repair yourself and there are companies out there that specialize in rebuilding them. Dirt cheap as a DIY project but having it done can set you back a hundred or two plus the downtime,

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**Author:** ![eddo](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/eddo/32/2594_2.png) [@eddo](https://community.cartalk.com/u/eddo)\
**Post date:** [March 5, 2021, 3:21pm UTC](https://community.cartalk.com/t/1999-ford-e150-hvac-issue/175536/6 "2021-03-05T15:21:51Z")

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if any under hood or under dash work has recently been done, look in those areas for a vacuum line that has been broken or knocked loose.

not that I’ve ever done that… 😉