The blower is fused at 40 amps. It has a 40 amp maxi fuse in the Power Distribution Center. That is why it can be bad but still not pop the fuse. Best thing to do is remove the fan and test it with power and ground, you could use jumper wires temporarily connected to the battery, put maybe a 20 amp fuse inline on the positive test wire and connect the positive to the green wire and the ground to the black wire on the fan motor. If it pops the fuse the fan motor is bad. I replaced my own fan not long ago, I bought a Factory Air fan from Advance and used an online discount and saved $30.00 on it.

If the fan runs OK with temporary power from the battery, the next logical problem could be the fan switch on the control head in the dash. It is not likely that it is bad though, all it does is provide ground to the resistor pack. You probably have a bad fan motor. That is what causes the resistor to go bad, usually when you lose the lower fan speeds it is because the fan is pulling too much current. The fan still works and is not bad enough to smoke the resistor but it burns out the lower fan speeds, which are determined by different levels of negative current supplied to the resistor by the fan switch on the dash.

Jimmy

 

I took the blower motor out today and it was nearly frozen up (rusty bearings I guess). I removed the rubber plug and put some oil in there, and then fired it up by hooking it directly to a booster pack, and eventually the fan started turning freely. I hooked it back up in the truck and it worked perfectly on all speeds. Fortunately that new resistor I bought was okay even though it overheated yesterday and melted a bit of its plastic plug housing (as I mentioned in a previous post).

I got the blinker issue fixed too. As it turned out, one of the bulbs on the front passenger side was only working intermittently. The bulb was fine but the contacts in the socket had whitish oxidation all over them. I cleaned that off and it works perfectly now.

Thanks for all the help.

 

Glad to know it was an easy fix for both problems.

Jimmy

 

you are better off replacing it I Guarantee it will lock up on you again soon the fan new is only $45 or less

 

I'll replace it when I need to. For now it is working perfectly and it didn't cost me anything.

 

It has now been a little over a year and it is still working perfectly. I think the key is to use it frequently, even in the summer. Just turn it on high for a few seconds whenever you go somewhere and that should keep it from freezing up due to rust.

 

Hi, back again. Have replaced the resister switch several times and recently wired in a new plug. Once again the blower has quit. Pulled the resistor and checked for the usual melting and it was in perfect shape, so now what. Checked fuse #25 and it was in good shape. Open to suggestions here.

 

What year is your truck Cowgirl?

 

Hello, Have been reading through and feel i'm going through the same issue. No matter if i place the fan controller on high, low, or in between, the fan and, or A/C wont work. I pulled the resistor and noticed scorched and stripped wires going into the connector. I'll be replacing the resistor shortly as i suppose its faulty. I'd like to get a new connector as well.

Could i buy one at the parts store or is that a dealer part?

I pulled the fan motor as well, and hooked it up to a 12 volt power supply i have, and it works smoothly. One thing i noticed was that prior to the fan loosing power on all speeds, the climate controller back lights weren't working. I thought that maybe i had the instrument cluster dimmer turned down, but it was on full brightness.

Is there any possible way that i burnt climate control back light bulb could cut the proper function of the fan blower?

And one last thing, I've been told that if the fan resistor goes bad, it should still work on low. Does the resistor get 12volts power before the fan motor?
Thanks before Hand. looking foward to getting this resolved.

 

I believe (don't quote me here) that the fan gets power from the fuse in the PDC, and grounds through the resistor via the speed selector. Nowhere connected to the illumination system.

Actual resistor values vary from manufacturer to manufacturer, but generally they are along the lines of High-0 ohms, Mid2- 0.4 ohms, Mid1- 0.8 ohms, Low- 1.5 ohms plus or minus a little (again, not all manuf's are the same).

Assume the fan is about 0.8 ohms:

14 volts @ (0.8 + 0.0) ohms = 17.5 amps.........17.5 amps * 0.0 ohms = 0.00 volts lost...........0.00 * 17.5 = 00 watts heat dissipated
14 volts @ (0.8 + 0.4) ohms = 11.6 amps.........11.6 amps * 0.4 ohms = 4.64 volts lost...........4.64 * 11.6 = 54 watts heat dissipated
14 volts @ (0.8 + 0.8) ohms = 8.75 amps.........8.75 amps * 0.8 ohms = 7.00 volts lost...........7.00 * 8.75 = 61 watts heat dissipated
14 volts @ (0.8 + 1.5) ohms = 6.08 amps.........6.08 amps * 1.5 ohms = 9.12 volts lost...........9.12 * 6.08 = 55 watts heat dissipated

And that's why the plastic melts....