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Electrical s10 blazer

We had a fan switch replaced on a s10 blazer. Now everytime it hits a bump the car loses power and so does the dash and it blows the fuses for the alternator and dash.

There are 2 fan switches on your Blazer. Which did you replace? The one in the dash or the one under the hood?

The dash. And now everytime you hit a bump it blows the dash and alternator fuses.

sounds like a loose wire shorting something and popping the fuses. Check around the switch you replaced.

What’s the Blazer’s model year? This is the switch for the heater/AC blower fan, right? Sounds like the repair was botched.

It’s a 1991. Everytime it hits a bump the dash and alternator fuses blow

They may have had to replace the blower switch connector, a common failure on some of those old vehicles, they burn up and some switches come with a new connector for that reason. Your shop may have done a sloppy job with the wiring causing a short.

Is it the 25 amp heater/ac fuse that is blowing? If so, I think Nevada’s comment is probably correct. It appears there’s a brown wire that carries the power coming from that fuse, through C235 (connector, 1 pin) to c205 (another connector, 4 pins). C205 is where the blower switch plugs in. The short could be in that area, or in the 3 wires (yellow, orange, and blue) that continue to the blower motor and resistor array.

The switch replacement might be a red herring.

Look for this with the side mount battery terminals on you’re ancient GM.


The most common problems that I recall dealing with on similar GM HVAC systems were the hi-fan relay and the fan speed resisters. I suggest that you remove and inspect the resister block and if it looks good remove the cap from the hi fan relay and inspect it. But of course, closely inspect all the wiring from the the red hi fan power source to the purple wire to the fan. You might try to blow the fuses by twisting and pulling on the harnesses at the high fan relay. The switch that you replaced has a brown wire delivering battery (+) through the firewall near the glove box and your description indicates that there is no problem with that circuit. But as mentioned above someone could have gotten rough getting the switch installed and crossed and shorted out the dash/charge circuit. But that would be some really shoddy work.