Cooling fan hi fuse keeps blowing

[thelastdon_62694]

I have an 07 Chevy Aveo,I notice my air only works good when I am moving,not really at all when I am sitting or at idol,so with the car in park and the air on hi after a few moments the car will blow the 30 amp fan hi fuse which causes the car to over heat...anyone have a good idea why,it would be so helpful,I will say I tested the relay and it it good

[avguy]

I recommend that you diagnose by testing, instead of looking for guesses from others.

[thelastdon_62694]

Thanks I did do a couple things but running down wires is one of my short comings...I thought maybe someone else ran into this problem

[avguy]

The resistor would be the first suspect, followed by the fan itself. But without testing, it's just hang a part and hope for the best.

[thelastdon_62694]

I tested the resistor...anyway to test the fan?

[avguy]

The best way would be to measure the draw, but doing that can trash a regular multi-meter fairly easily. A less precise, but safer way would be to just run a test of the fan powered directly from the battery. Attach a 30A fuse to a wire (16 gauge house wire, etc), and connect that directly from B+ to pin #2 of the fan. Then connect another wire from battery negative to pin #1 of the fan. If the fan itself is the problem, the fuse should blow fairly quickly.

[thelastdon_62694]

Can someone tell me how to test the resistor...maybe I did it wrong 🤷🏻*♂️

[JB_Fraser]

If you follow avguy’s Post you can verify if the fan has the issue (excessive friction on bearings/bushing or damaged coil) which would cause higher current draw. If that works okay then you can rule out the fan and take a look at the wiring. To check the resistor you can disconnect the fan connector and pull fuses for fan hi&low. Measure with your multimeter on ohms and see if it is open (at these currents the resistance is going to be very low). Alternately , you could measure the voltage drop across the resistor with the fan low circuitry running and (I make an assumption here that fan runs around half speed) you should see around 6 volts across the resistor..

its possible your fan low low circuit could be defective and causing the fan hi circuit to cycle off and on more often than it was designed too(another assumption).

Cheers

[thelastdon_62694]

Thanks for the reply!!! Yes I did the fan trick,a good one to have in my arsenal...the fan worked flawless and as I had hoped since mine broke about a year ago...ok so I am going to try the fan connector and try the ohms..I am not sure I quite underhand it but I am on my way!!!

[JB_Fraser]

When measuring resistance on your multimeter of the ceramic resistor, you want to make sure it is isolated from any voltages or other resistive loops it may be connected too as this will throw off your reading. I figured the easiest way to isolate it without using any tools was to disconnect the fan connector and fuses/relays associated to it before checking the resistance.
There is a fan circuit on the forum that have been posted by other members for reference.

Cheers