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Blower motor speed increases but doesn't decrease
#1
Blower motor speed increases but doesn't decrease
Hi, I have a '03 Chevy 2500HD 4x4 6.0. I am having a problem with the blower motor speeds. When I start at speed 1 and go through 2, 3, 4, and 5 they all work correctly. When I go from 5, 4, 3, 2, 1 it is stuck on 5. When I turn the control off the blower goes off then I can start working my way back up until I get to the speed I want. This has been happening for a while and recently only some of the speeds worked. That told me the resistor went out and I had to replace it. So I did tonight. Now I still have the same condition of being able to turn it up but not down. I have a feeling the reason the resistor went out was because I was constantly turning the blower off and back on to get the speed I want. Is this a Climate Control Module (located in the face of the dash) or a Blower Motor Relay (located on the evaporator housing) or something in between? Any suggestions?
#2
I did a little research today and a couple things may be incorrect about my last post. First, the only place I could find a relay was Autozone and it said it was on the evaporator housing. After looking at a schematic, I found that the blower motor relay was part of the resistor assembly. I have replaced that and still have issues. The other thing is that when I started turning it from 1 to 2,3,4 there was a noticable change in airflow. When I went from 4 to 5 I could not feel a difference. Whether there was or not would require checking the voltage to see if there was an increase. I may end up doing that even if it doesn't really tell me what the problem is. So it is down to the control module and wire harness. Because this is a manual contol module I can't imagine there is a problem with the switch. The way it acts it sounds like some kind of logic control gone crazy. Any ideas would be much appreciated!
#3
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I think you may be going down the wrong path. The A/C control in the dash is electronic and can go bad. Unfortunately, that part is a dealer item, so if it is determined that part is bad, you don't have a choice.
The other possibility is the Body control module....this also makes decisions related to the climate control.
The BCM is available, but requires programming after installed. This can be done at a dealer or qualified repair shop that has the correct tools.
2003 Chevrolet Silverado 2500 Hd Body Control Module - AC Delco, Cardone - TheAutoPartsShop - TheAutoPartsShop
This may be a situation where a professional diagnosis is needed.
The other possibility is the Body control module....this also makes decisions related to the climate control.
The BCM is available, but requires programming after installed. This can be done at a dealer or qualified repair shop that has the correct tools.
2003 Chevrolet Silverado 2500 Hd Body Control Module - AC Delco, Cardone - TheAutoPartsShop - TheAutoPartsShop
This may be a situation where a professional diagnosis is needed.
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larryboy58
Silverado & Fullsize Pick-ups
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September 5th, 2009 7:24 AM