Unpredictable Fan

[MRundel]

01 (Job 2). 95% of the time my fan on the AC- heater works fine. The rest of the time it will not work. Turning the knob makes no difference, turning the AC or heater on and off makes no difference. I may be driving down the road and all the sudden it starts working properly again. Heat index today is predicted to reach 102 so AC is good.

Usually I've noticed the failure on start up. As far as I know my battery is fine with no indication of low voltage but I'll get it checked. Any other suggestions on what to look for?

 

[MRundel]

The fan has now become completely predictable, it has stopped working. I checked the connection on the blower, the fuse for the relay, the relay and the fuse for the blower controller. I guess the next step is to pull the dash trim piece and check the switch. I'll try a multi-tester to check for current. Does anyone know where the blower controller is located and how to check it? Any other ideas or suggestions?

 

[Bobmbx]

The fan has now become completely predictable, it has stopped working. I checked the connection on the blower, the fuse for the relay, the relay and the fuse for the blower controller. I guess the next step is to pull the dash trim piece and check the switch. I'll try a multi-tester to check for current. Does anyone know where the blower controller is located and how to check it? Any other ideas or suggestions?

Its your blower motor resistor. An easy fix, relatively speaking.

 

[MRundel]

Did some research, what it disclosed is usually if the resister fails, the blower defaults to blowing on high regardless of what position the switch may be in. Mine is not working at all. That same research indicates the blower motor is known to failure. It's a cheap but some what laborious fix. I'll try to "hotwire" the motor directly and see if it runs.

Electrical issues are so much fun........

 

[Bobmbx]

Did some research, what it disclosed is usually if the resister fails, the blower defaults to blowing on high regardless of what position the switch may be in. Mine is not working at all. That same research indicates the blower motor is known to failure. It's a cheap but some what laborious fix. I'll try to "hotwire" the motor directly and see if it runs.

Electrical issues are so much fun........

Erh....if the resistor fails, all you have left will be "high" (high doesn't route through the resistor). Since you have no blower at all, your suspects are, as you say, the blower itself or the blower relay.

How old is the blower? While you're down there, take the opportunity to clean out your airbox and drop new resistor in. Its cheap enough.

 

[MRundel]

It only has 196000 miles on it. 4wd, tonneau cover, bed extender, leather, straight body, two owner ST for only $2500. I figure I can spend some on it!!

I swapped the relay around and checked the fuses. I'm thinking its probably the motor but I'll by-pass the wiring and see if a direct line makes it run. If I pull the motor I'll probably do the resister while I'm there since the parts costs are minimal.

thanks.

 

[roamer37]

The normal for the blower motor resistor is the connector gets hot melts the plastic and the spade connectors and or wires melt and make a open. I would check it, easy on the passenger side just below the blower motor see if you can even get it off. If it comes off check all the wires you can jump the blower motor from there..

 

[MRundel]

After doing a little more research, and finally having a little time to play, I tried a suggested testing method. After turning the ignition and the fan on, I raised the hood and tapped the blower motor with a hammer, it started running. That means its likely a blower motor which is available at O'Reilly's for approx $40. I'll add this to next weekend's project list.

 

[MRundel]

Problem solved. Fan was $45 with tax at O'Reilly's. Had to pull the cruise control unit and had to loosen the reservoir tank cluster for washer fluid and coolant. Its a tight wiggle to get in and out. The replacement has a pig tail plug that matches and not a plug on the side of the motor, this actually makes it easier to connect once installed.

Cold air is nice.

Thanks to those you replied to my request for help.