# 92 Chevy thumping

**URL:** <https://community.cartalk.com/t/92-chevy-thumping/24137>\
**Category:** Maintenance/Repairs\
**Created:** [December 31, 2008, 1:46am UTC](https://community.cartalk.com/t/92-chevy-thumping/24137 "2008-12-31T01:46:26Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![rditchen](https://avatars.discourse-cdn.com/v4/letter/r/ed655f/32.png) [@rditchen](https://community.cartalk.com/u/rditchen)\
**Post date:** [December 31, 2008, 1:46am UTC](https://community.cartalk.com/t/92-chevy-thumping/24137/1 "2008-12-31T01:46:26Z")

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I have a 92 Silverado when you turn the key on or off it thumps under right side dash. Sounds like a vent door. What is the problem?

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**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\
**Post date:** [December 31, 2008, 3:05am UTC](https://community.cartalk.com/t/92-chevy-thumping/24137/2 "2008-12-31T03:05:42Z")

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It’s the interior vent motor. This opens the interior of the vehicle to the outside so that when the doors are closed, a pressure isn’t created to prevent the doors from closing. A common problem.

Tester