trbsami

Might make a new thread? 2006 Express 3500 6L cargo. New blower motor, resistor, harness, 3-dial control panel inside. Still no heat or AC, blower not working at any speed. Blend doors do move, so I THINK? I'm getting good vacuum. Fuses and relays good under the hood. There are 2 fuses under driver`s seat that say hvac and hvac1. they don`t seem to be getting power to them. (fuses themselves are good) Where do I go from here?

mountainmanjoe

well you piggybacked on someone who stated their blower is working so it's unrelated. So yes you should make new thread. I moved it for you.

Did you test the blower to make sure it works?

trbsami

Thanks. Motor runs fine being powered directly. No power gets out to it from the resistor. I pulled the 6-wire harness loose from the resistor and the only power is the fat red wire on the far right- I`m assuming it`s the main power in. Can`t detect any signals coming to any other wires even with changing settings on the controls inside. The old harness had the fat black wire terminal burned a bit. (3rd from the right)

mountainmanjoe

This is the wiring diagram for your system
2006 Express / Savana electrical - Body - HVAC - Chevy & GMC Vans

The red wire only supplies power in high speed setting. Since the blower doesn't come on at any speed, then it's something common to all the circuits.
There could be damage/corrosion to the blower motor connector. When the motors seize, it causes heating and arcing anywhere the connection is poor.
Or the control panel power isn't reaching the assembly.

How to test the ground:
Put your DMM in resistance range. Put your negative probe lead on your battery negative post, and touch positive probe to pin C on resistor assembly harness (Black). It should measure less than 1 ohm.

Eliminate control panel as a cause:
Apply 12V to pin B on resistor assembly socket. Fan should come on full speed.

trbsami

I get 12V to the red wire in all fan speed settings.
OHM reading on C of 1.9- assuming weak/ bad ground somewhere?
12V applied to B gets me a click sound and no fan running. I can jump the fan directly at the motor and it runs fine. Again, all these parts are new.

trbsami

When should i get power to the #9 and 10 fuses under the seat? There doesn`t seem to be any power there?

mountainmanjoe

There's supposed power on the wire all the time. As the diagram shows, power then goes through the high speed relay which gets switched on with the control panel.


It's a little bit too much resistance, but not enough to keep it from working.
the page I linked shows the ground location.
Make sure your probe tips are touching good clean metal though.

you may have a bad resistor module then. Trying putting power on E, D, & F as well.

trbsami

Thanks for your patience and working through this with me! More testing reveals I have E,F,and D working fine. B just clicks. This is with ground jumped direct to battery and power jumped straight from battery.
Tomorrow I will clean up my grounds and swap out the resistor.

mountainmanjoe

For the sake of clarity: the string of three low speed resistors, plus the high speed relay, together comprise what is referred to in the diagram as the "Blower Motor Resistor Assembly" (I called it "module" in my last post)

Since your test of pins E, F & D was good, it means the three individual resistors are actually fine. 'B' should have switched on the relay which turns the blower on full, so relay must be bad (though it's strange that it still clicks). If you can replace just the relay you can do that, but if you're not comfortable servicing it then you can replace the assembly. Make sure you get a good quality one, not a knockoff. Was the one you said you replaced an OEM part?


The fact that the motor worked in your test shows that the ground is OK (which I expected. It's shared with other systems like ignition so you would have noticed problems). But go ahead and check it anyway.

trbsami

Update: Mechanic found a bad ignition switch. No power to the fuses under the driver`s seat was relevant. Replaced it, so the blower and temperature selector work fine. Blend doors are stuck on defrost. Assuming a vacuum leak somewhere?