dnschons@gmail.com

I've taken thd whole dash apart .
Checked all fuses right n left. ,
Cannot find resistor which I think is the problem. I've looked under every plastic box which I was told on this forum where it is . Cannot find it . I drove it later and the fan came on and then turned off . A short somewhere. ???? It is a 94 pickup. 4x4 xtra cab dlx basic version . I'm at a loss. Sounds like a short . Can I get a first place to look. Not sue where to start. .
Thank you for any help

wyoming9

iTrader: (1)

First the blower motor will always work when the switch is in the high position. In high the resistor is out of the circuit.

It is mounted into the heater box into the duct so the moving air can cool the resistor .Not real sure just where on the 94

From the thermal cycling they get quite brittle so don`t waste time trying to get a used one.

It comes down to a bad resistor

bad switch It is a switched ground so the blower motor grounds through the switch.

bad motor

Loose connection someplace in the circuit.

scope103

All answers are found in The Good Book. http://personal.utulsa.edu/~nathan-b...g/25heater.pdf

Wyoming9's description sounds correct to me. The most common failure of the resistor is one of the resistance components opens up, which still allows the blower to run on high. So, yes, you've got an intermittent "open" somewhere. This (like all electrical problems) will never be solved without a multimeter. No excuse to not have one.

dnschons@gmail.com

Ok I have the multimeter . How exactly do you check wires with it. Electric is not my strong suit.
Another thing is when I drive I'm keeping the fan on . Sometimes I will start car and fan works , other times not. . I hit a bump in the road and the fan turned on . Hmmmm, maybe a short. ???
I've jostled a the wires and could not start fan.
An earlier post said to look for resistor in the fan box. I have 3 boxes under center if dash and to the passenger side. In not sure which box , but even worse is that I gave taken every screw out of said boxes and cannot open them. . how do I open them ???
BTW , how do I post a picture on this thread????

wyoming9

iTrader: (1)

Who knows what you might have done now taking things apart.

Does your fan work with the switch in the high position??

Some of these motors had brushes some did not

You can use your multimeter to check for voltage set on DC voltage.

tsh2014

Change the Blower Resistor. It is behind and underneath your Blower Fan. Easy to change, use a phillips screwdriver. No need to take the fan apart. See my thread here, about halfway down:

https://www.yotatech.com/forums/f116...issues-281702/