No power to blower resistor?

ELTHEOMUNDO

MEMBER
2005 CHEVROLET MONTE CARLO
3.8L
V6
2WD
AUTOMATIC
150,000 MILES

My blower stopped working in the cabin. I checked all fuses with a test light. Fuses were good. I have a good ground on the input to the blower resistor. However, the test light failed on the power input. From your wiring diagram for 2005 monte ss, it shows the 30 amp under hood fuse going directly to blower resistor input. I think when a shop dud my water pump, they got rough with the wires. I was able to back probe the power direct to battery to test my theory. The blower worked at all speeds like it should. My next challenge is finding where wire is bad, or running a new wire. Are there diagrams of the wiring harness that comes out of the top fusebox so I know which wire to test? Can I simply run a new wire from fuse box to blower resistor and bypass harness? Can I run a wire like a stereo amp power wire with an inline fuse from battery and avoid the regular fuse box all together? Not much info I could find on wiring, and they Haynes manual is junk, it doesn't show that 30 amp under hood fuse going directly to blower resistor.

Monday, October 14th, 2024 AT 1:42 PM

3 Replies

KEN L

MASTER CERTIFIED MECHANIC
51,853 POSTS

Yep, the power to the resistor comes directly from the 30 amp HVAC blower motor fuse in the under hood fuse panel, (red wire), here is guide to help you test for power and the blower motor wiring diagrams so you can see how the system works and which wires to test. Check out the images (below). Please let us know what happens.

Images (Click to make bigger)

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Tuesday, October 15th, 2024 AT 10:00 AM

ELTHEOMUNDO

MEMBER
2 POSTS

So, what is funny is I traced back from the blower resistor positive, and it doesn't go directly to the source under hood. It goes into another wiring harness behind the stereo. I ended up pulling the dash and pulled HVAC controls and stereo. Aftermarket stereo is double dining goes deep into dash, so much so the plastic behind it was cut. The wiring harness was behind it. Just for grins, I hooked the controls back up and turned on car with radio pulled, worked perfectly. Couldn't see any issues with wiring. Pushed radio back in after trying to better organize all the wires from radio. Blower still worked. Put dash back on and all still worked. I have electrical gremlins. If it happens again, I will further inspect behind dash. I was just going to pull a new 10 ga wire through where the rest of wires come through, but saw there was a sort of sealed boot and didn't want to open that up for chances of moisture and salt getting in. Ken, your diagram is much better than Haynes, where do you get the good ones from? Super-secret pro manual shop book?

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Tuesday, October 15th, 2024 AT 11:03 AM

KEN L