Silverago Fan runs only on high

[Hookmaster]

I hopped in the 2004 Silverado on Saturday and the fan only worked on high. It has been working on all speeds before that. I asked a friend with a Tahoe and he said this happened to him and some module needed replacing. Any help on what part it is and where it is located?

[PierBridge]

Blower resistor board.......Located in the heater box under the dash passenger side.

[Shack]

I second a blower motor resistor. Should be easy to replace.

[Hookmaster]

Do I just pull out the old board and put in the new? Do you need to disconnect any power or am I good to go with the key off?

[Macgyver55]

Good to go with key off. Shoud be 2 (maybe three) screws holding the resistor board in place. Just unplug, remove, put in the new resistor, plug back in and turn on the key. Should have all the speeds then.

[Hookmaster]

So am I replacing just the resistor on the board or the whole board?

[Macgyver55]

The whole board. I think they run 40 bucks or so (retail) if I remember....

[hanson]

Hookmaster-

Let us know how the repair works out for you, I have to do this to my GMC Sierra as well but unfortunately its not at the top of my list priority wise so I've been putting it off.

[Tom Linderholm]

Interesting, my 2003 Silverado has the same issue. Please do share if this is the cure.

Thanks.

[Jeremy airjer W]

 Originally Posted By: hanson

Hookmaster-

Let us know how the repair works out for you, I have to do this to my GMC Sierra as well but unfortunately its not at the top of my list priority wise so I've been putting it off.

You still haven't done that.

The reason why high works is that it bypasses all the resistors to allow the full 12 volts to reach the blower. Likely the resistor that controls the next speed down from high has gone bad since all the other lower speeds use that resistor the regulate the voltage to the blower.

[Hookmaster]

I'm going to try and get the part tonight and put it in before the cold weather. I think I may have lost the #1 fan setting a while ago. I checked it with a small strip of napkin and the #1 setting moved no air. As of Saturday, I turn the fan speed setting from 0-4 and nothing happens. Going to 5 (high) I hear a click and the fan comes blasting on. I also hear a some intermittent clicks in the back of the cab (crew cab). Does this have something to do with the flow through cabin ventilation?

[Hookmaster]

The blower resistor board was the fix. The part # for my 2004 Silverado Crew Cab was 89019088. This was for a bench seat, not the floor console model. It's best to have the VIN# to make sure you get the right part. It was held on by two hex nut screws. It should have taken 30 minutes but it took me 1 hour since the screw above the hump for the shroud was a little tricky to put back in. I now have air movement on setting #1 which I didn't have before. I also noticed that on long freeway trips I needed to put the fan on #3 instead of #2 last fall. So it gave some indication it was failing before it went belly up. The part cost $53.99 with the tax so I probably saved $50-$100 in labor.

I told my daughter I was going to post on Fishing MN about the issue and I would have the fix in 1 day or less. Well it took less than 25 minutes!!! Of all the non-fishing advice on this HSOforum, the car/truck stuff is some of the most valuable since the non-mechanics can fix stuff but we don't know where to start. Thanks to all who responded.

[Jeremy airjer W]

Glad to hear its fixed!!

We have a good bunch of experienced automotive people here. I'm sure they would agree that it is there/our pleasure to help!!