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Discussion Starter · #1 ·
So the other day I got in my truck and the A/C blower would not come on. After fiddling with the controls a bit I gave up and rolled the windows down. About five minutes later it was eating at me so I switched the control from off to max and the fan kicked on like it was supposed to and was blowing cold air. Since then, every once in a while I notice that the fan doesn't come on when I start the truck, or if it does it's very weak, so I crank it to max, the fan blows noticeably, then I turn it down to a more reasonable setting.

Since I've had this truck, the low setting on the fan has always been pretty pathetic, but I had nothing else to go off of, so I was like, whatever, and let it roll. Now that I'm having this intermittent "no blow" from the fan, I'm determined to find the root of the issue and correct it.

I posted in another thread, but nobody replied, so I figured I'd start a new one. I saw where the blower fan resistor can go bad, so I've got one of those on the way from Amazon.com. I figured with 100k on the truck, it can't hurt to change out a $30 part anyway. Are there any other parts that I should be looking at as possible culprits? Thanks for your input.
 

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Couple of questions.
1. Is it just the blower that is intermittent or is the AC compressor engaging also intermittent?
2. Is your fan speed control a variable speed or does it have individual set speeds that can be selected for example, Off, 1, 2, 3, and so on?
 

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Discussion Starter · #4 ·
rollover said:
Couple of questions.
1. Is it just the blower that is intermittent or is the AC compressor engaging also intermittent?
2. Is your fan speed control a variable speed or does it have individual set speeds that can be selected for example, Off, 1, 2, 3, and so on?
Just the blower is intermittent, not the compressor.

Fan speed does not have set speeds, it's more like a rheostat. It has the rotary control.

If the blower motor resistor harness is burned, what do you do about it? pull the wires and repin into a new plug? Why are they notorious for burning?
 

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Most aftermarket companies, NAPA CARQUEST ADVANCE will have replacement plugs you can splice in for about half the price of a GM plug kit, and they burn up because GM cheaped out on the size of the terminals and they get hot, when they get hot they loose tension which causes them the get really hot and melt the plastic plug.
 

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I had an 01 impala where the blower resistor module went and had the same symptoms. Its a little different style but same technology in these trucks so I would assume it would be the same thing.

Rockauto has them for like 30 bucks so it isnt a huge parts cannon projectile to try.

Part # on rockauto ACDELCO 1581638
 

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The electrical schematic indicated it has a rheostat for fan speed control I just wanted to be sure that is what you have. Rheostats can get bad spots (worn or dirty) that will cause intermittent operation when you stop the control at one of these spots. Try cleaning it by cycling the control from minimum to maximum rapidly a dozen times or so with the truck off. If that does not work you could take the HVAC controller out and try to get some spray electrical contact cleaner inside the rheostat and again swiping it a number of times.
 

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Discussion Starter · #9 ·
Well I have the blower motor resistor on the way from Amazon, and I have some fancy aviation electrical contact cleaner, so I'll try replacing the resistor and cleaning the rheostat and see how that works out for me.
 

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I am not so sure you have a "resistor". The rheostat is a variable resistor whereby you get an infinite number of speeds. Those of us that have a discrete number of fan speeds have a set of resistors whereby the fan speed switch selects a different resistor and thus a different fan speed. The failure mode on these is one or two of the resistors blow and you end up with just a few of the fan speeds or as previously mentioned the connector burns up and you have no fan speeds.
 

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Discussion Starter · #11 ·
The part I bought is the blower control module that goes next to the blower motor.

ACDelco 15-81638 GM Original Equipment Heating and Air Conditioning Blower Control Module
4.5 out of 5 stars 38 Reviews

Price: $28.98 Free Shipping for Prime Members
Note: Available at a lower price from other sellers, potentially without free Prime shipping.
In Stock.
 

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Discussion Starter · #13 ·
Well I installed the blower motor resistor. The fan is definitely blowing on all speeds now, it just seems super weak on the lower speeds, so I've got an ACDelco 15-81676 GM Original Equipment Heating and Air Conditioning Blower Motor on the way. Maybe it was a waste of money, maybe not. Either way, it can't hurt installing new components.

The resistor that I replaced looked old and a little corroded. All of the connectors were perfectly fine. I inspected what I could see on the inside of the A/C vent system and it didn't look dusty or clogged, so that's a good thing. I decided to go with the fan because on low speeds you can hear a little "tick" as it rotates; kind of sounds like the motor is tired. We'll see how it goes.
 

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Discussion Starter · #18 ·
djlove said:
where is the resistor located? Still up by the blower motor?
Yeah. Super easy to change. Two torx head screws holding it in. It's really easy to get to if you push the glove box stop up and let the glove box fold down. Do that and you have great access to it. Took me maybe 3 minutes to change it out.
 
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