Just happened! No warning. The only fan speed that works is "high". None of the other speeds at all.
Fuse? Some mysterious relay?

Any help is always appreciated.

 

Likely the resistor block that is in the heater plenum under the hood. It has multiple resistors to lower the voltage and allow for different speeds. In HI, the resistors are all bypassed, and electricity flows directly to the motor.
There should be a connector with several wires very near the blower motor. The wires should lead over to the blower motor. Disconnect it, and you can then remove the resistor pack. It will have several coils that look like toaster wire.
tom

 

There aren't expensive....it's a high failure item for Ford....I always carried a spare for my old '92 F250.

 

Great!
What's a plenum? Is that the same as the blower motor resistor?
Too much trouble to ask for a picture? Can't find it in my (stinking) Haynes manual!

 

A plenum is a chamber for air. It generally is used in a ducting system.
You want to open the hood, and find the blower fan motor. It will be mounted onto a box, with wires leading out of it. Follow the wires to a thing plugged into the same or a nearby box, generally closer to the centerline of the truck than the blower motor. The plug is connected to the dropping resistor pack, which is hidden inside the box, for cooling air flow, and to prevent it from getting rained upon.
If you stand on the passenger side by the front tire, look to your left and down and you should see a black plastic or fiber box with a cylindrical motor body sticking out. It will be about 3-3.5" in diameter, and close to 6" in length, and will have a wire or two coming out of it that goes over to the resistor pack, again screwed into the same box.
I don't have a picture, or I could have saved ~1k words... heh
tom

 

I found it! 1 harness . . . 2 screws . . . out!

Hope it fixes it. No way of testing it I suppose?
I'll run it by a multi tester for continuity.

Thanks all!!!!!!!!!

 

Look closely and you'll likely find that one of the wires(coiled looking things) is broken or loose/burnt looking under a rivet. Unless the dash switch is faulty, which could happen, but what are the odds that ALL the low speeds would die at the same time?
tom

 

Can anyone tell me if there is something else that can cause this to happen? I have a 2008 Ford Escape that only blows on the 4th speed setting. I have already changed the resistor and still nothing except for the 4th setting option.

 

bobturner this thread is from 2009. We will have to unwrap the mummy ...

Loose connection at the switch, bad switch, or damaged wires between the switch and the resistor pack.
Unless 2008 went to a pulsed-power control for infinite speed settings used by an automatic temperature control system, the resistor pack & switch control blower motor speed. There's not much more to it.
tom