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Heater/AC Fan speed control

Posted by jerry_nj (My Page) on
Thu, Feb 3, 11 at 20:35

My 2005 Chevy Colorado pickup truck seems to have only one fan speed on the HVAC system, the highest speed. There are 4 speed positions on the control.

Is there a modern pulse width modulation speed control on this vehicle (or any vehicle in the lower cost models)?

I have no idea how to approach trouble shooting as I don't know what to expect on the terminals of the speed control switch. I do not have a shop manual.

The fan runs on the highest speed, so I conclude the motor isn't the problem, unless there are different windings on the motor for the different speeds. Is the speed set by the amount of power delivered to the motor, i.e., less pulse width, or fewer windings for slower speeds?

Follow-Up Postings:

RE: Heater/AC Fan speed control

Jerry, I would say it is the blower motor resistor. Check out this site. It does a better job of explaining the repair than I can. The repair is for a 2004. But I would think that yours is the same.

HTH and
Good Luck

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