In my 89 Ranger the heater fan only works on the highest setting. I thought first it was the motor because when my buddy borrowed the fan for his Ranger it only worked on hi too. But this weekend I tried it with 3 different fans, and they all worked only on hi as well, which leads me to believe it's either the switch or the resistor. In your experiences, which has been more prone to keep the fan from working in all settings, switch or resistor? Where is the resistor located so I can troubleshoot it? I suppose I have to get out the multimeter and do a bunch of testing to see when/where I'm getting/not getting power.

 

The blower resistor is shot. Look under the hood, it plugs into the plastic blower duct with 4 or 5 heavy wires attached. Get a new one at Napa or Autozone for about 20 bucks.

 

Did the F150 use the same resistor?

 

If it has manual heat/AC controls, it has the resistor. If it has that idiotic auto climate control, it has an electronic blower motor controller which is about 120 bucks.

 

Problem solved.....mostly.....

My old 87 F150 had the same resistor as the Ranger. Went to remove the resistor from the Ranger, the plug was so badly corroded I couldn't get it out. So out come the side cutters, removed the plug & resistor from the Ranger, and the plug from the F150, and spliced in the F150 plug into the Ranger wiring harness (after verifying wire colours and pin positions, of course). Now I have speeds 1, 2, & 4. For some reason speed #3 still isn't working, could be a bad connection (the green wire) that I will revisit after the cold snap is over. But at least I have a couple lower speeds now, instead of turning it off & on. Thanks for the help

 

And thanks for the update, glad to hear it's fixed.

 

Check the wiring at the connector, they get damaged a lot.