Had the heat on full blast yesterday and all of a sudden in stopped blowing. Now after restarting the truck and turning the switch, no air comes out of the vents whether it is on cold or hot, at any speed. I am going to get a new resistor for the blower motor right now to see if that solves the problem, but are there are other quick fixes I should check first before I rip apart the dash and replace the blower motor? Any fuses I should check and where they are located? I have done some searching and that's how I got the idea to replace the resistor, but any other help is appreciated! It is on a 2002 Dak Quad Cab 4.7 if that matters.

 

I have an 03 with 4.7...

If you have a fan that blows on high but not on other settings, that is the resistor. If you have a fan that doesn't blow at all, or blows intermittently, that's the motor. FYI, it's common for both of them to go. My motor burnt out one resistor, and then burnt itself up a few months later, along with another resistor.

Of course, check all of your connections and fuses first but remove the resistor and inspect it. It will look "cooked" inside the harness if the blower is burning it up...

 

There is no need to rip out the dash, blower motor resistor is located in the passenger's foot well, in the bottom side of the HVAC housing to the left of the blower fan. It is easier to R&R the resistor if you remove the heater vent duct first.

You might check the green wire on the fan and see that it has power, it has a 40 amp fuse in the Power Distribution Center. The fan itself could be locked up, you might remove it and see if you can get it to spin with voltage and ground supplied temporarily from the battery.

If the fan works again after replacing the resistor, check the current draw of the fan. If it is pulling more than 17 or 18 amps with the engine running and the fan speed on high the fan is bad and it may destroy the new resistor. You may need to replace the resistor and the fan both to completely fix the problem. You could also have a bad fan **** on the climate control panel, but that may not be the likely cause of the fan problem. Usually it's the resistor that goes bad and you lose operation of the blower fan.

Jimmy

 

So just changed the resistor and everything works now. Saw where the blower motor was as well while I was under there. The connections looked good nothing looked burnt or charred.
Jimmy, how do you test the draw of the fan? I want to do that and make sure it is ok and not drawing too much.

 

You need a clamp-style ammeter to measure the current draw. I bought this one for myself at Christmas in 2011:

http://www.craftsman.com/craftsman-d...1&blockType=L1

You need to remove the plastic push-in wire retainers from the right side of the blower motor and drop the green and black wires down so you can unplug the wire connectors. The wires are twisted together and you need to un-twist them so you can get the clamp around the green wire. Then you can plug the connector back together and measure how much current the fan draws. Most regular volt meters with probes will only measure current up to 10 amps, if you try to measure higher current than that it will pop the internal fuse in the meter.

I like that little Craftsman meter, it also measures AC and DC volts and has a continuity tester too. It works very well for how I use it.

Jimmy

 

That's exactly what I did. The easiest way to know, at this point, will be if that new resistor blows in a few weeks/months, you can assume the blower is bad. Luckily, that resistor is pretty cheap.

 

Only problem with that approach is the next time you may end up with a melted connector and wires.

Not good

Thats a lot harder to fix

 

True...

If that does happen, the junkyard will be your friend, OP.