# Heater/air conditioning fan speed control

**URL:** <https://community.cartalk.com/t/heater-air-conditioning-fan-speed-control/29905>\
**Category:** Maintenance/Repairs\
**Created:** [May 2, 2009, 5:48pm UTC](https://community.cartalk.com/t/heater-air-conditioning-fan-speed-control/29905 "2009-05-02T17:48:59Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![mongo1](https://avatars.discourse-cdn.com/v4/letter/m/5daacb/32.png) [@mongo1](https://community.cartalk.com/u/mongo1)\
**Post date:** [May 2, 2009, 5:48pm UTC](https://community.cartalk.com/t/heater-air-conditioning-fan-speed-control/29905/1 "2009-05-02T17:48:59Z")

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I am having a problem with my fan switch. I drive a 2003 GMC Sierra 1500. The fan only runs in the high mode. It will not run at any other setting. Is there a resister in the switch, or else where in the circuit, that needs to be changed? If so where can I find it? Or do I need a new fan motor or switch?

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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:** [May 2, 2009, 5:56pm UTC](https://community.cartalk.com/t/heater-air-conditioning-fan-speed-control/29905/2 "2009-05-02T17:56:52Z")

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Is there a resister in the switch, or else where in the circuit, that needs to be changed?

You guess right. However it is likely located under the dash attached to the ducts so the resistors are cooled in the air flow. The part is called a resistor pack. They are generally not too expensive, or some you can rebuild if you are really cheap. The problem is getting to them. On many cars that requires a very flexible teenager with small long fingers.

A repair manual (available at the library or the auto parts store) should be able to guide you to where it should be.

Good Luck

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**Author:** ![mongo1](https://avatars.discourse-cdn.com/v4/letter/m/5daacb/32.png) [@mongo1](https://community.cartalk.com/u/mongo1)\
**Post date:** [May 2, 2009, 6:17pm UTC](https://community.cartalk.com/t/heater-air-conditioning-fan-speed-control/29905/3 "2009-05-02T18:17:25Z")

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Thanks for the help, I just have to locate it and repair. Thanks again.

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**Author:** ![super3889](https://avatars.discourse-cdn.com/v4/letter/s/c37758/32.png) [@super3889](https://community.cartalk.com/u/super3889)\
**Post date:** [May 2, 2009, 6:46pm UTC](https://community.cartalk.com/t/heater-air-conditioning-fan-speed-control/29905/4 "2009-05-02T18:46:13Z")

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resistor should be located on bottom of duct system in passenger compartment