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HVAC fan will not blow in any of the settings.

303 Views 13 Replies 5 Participants Last post by  davester3500
I have a 2008 3/4 to with automatic two sided climate control. The panel is lit up correctly but the fan will not blow in any of the settings. I’m about to drop the passenger side panel to look at the resister.

From looking at the posts it seems the resister is usually the culprit. Any advice on how to handle this rather than firing the parts cannon at it? Thanks.
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Here is the resister assembly.

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And here is the fan. You press a tab and rotate the body counter clockwise. nd

I tested the system with the resister and fan assembly lying on the floor. With the key in the ignition and turned to auxillary
The fan rotated feebly at the lowest speed. There are six positions on the digital readout. I increased the speed by pushing the manual speed button. The fan sped up a bit and then on position 6 it literally took off.
In the automatic mode the fan speed was 5 which is still feeble.

Looks to me it’s the resister. Having said that, I’ve see websites recommending both when either one fails.
I’ll see what’s available in town. Thanks for reading this. Any other tips are greatly appreciated.





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glad you are figuring it out, keep us posted
I'm not sure of a method for actual testing, but it sure seems like the resistor to me. That controls the fan speeds. And yours does look a bit crusty. I would do just the resistor and not put a new motor in it. It is not that hard to get to if the motor fails down the line, but it seems to be working for now.
I agree with Neal. That resistor looks like it's gotten plenty hot.
Hi everyone, I purchased a resister as shown. I plugged it in and plugged the fan back in. Unfortuneately the fan only ran well at top speed. I had varying speeds that were sporadic. I’ll try get some resistance readings.

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Did you repair the plug that plugs into the resister? May need to check the wires along the harness if something got hot.
With the new resister module plugged in, I manually increased the speed with the electronic controls then decreased them. There was a ticking noise present and the fan was weak but sped up. In position 5 it started surging and in position 6 it “ took right off”. I then went back down with the settings and it reacted the same as the climb up. The ticking makes me suspect something is wrong with the fan itself.
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The wire’s and connectors look good.
The black connector has the signal wire from the HVAC module. Measuring between it and ground, it was 6 V at the lowest speed and 11.6 V at the highest speed, with 12.2 V indicated at the battery. The increments at level 2,3,4 and 5 were petty much linear in between.
Here is the end of the black connector to the resister module. If you run voltmeter leads across the signal wire shown with the red circle, and the ground wire, shown with the green circle, the voltages change as you increase the fan speed.

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Now for the rest of the story. The fan was kaput. I installed a new fan after I already installed the new resister and it works great. Thanks everyone , for your helpful posts.

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thanks for following up with the results.
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