I posted this in HVAC, and perhaps it belongs here. Sorry for the double post.

I drive a '96 E150 with front and rear air. The other day the front blower suddenly quit, while the rear air (same control panel) blows cold.
Replaced the 60amp blower fuse under the hood, still nothing.
Slammed the door getting back in, and the fan came back on, but after shutting it off, no amount of door slamming helps.
Since the fan works on none of the speeds, should I first look at the switch on the dash, or the resistor?
Thanks in advance.

 

Probably time for a new blower motor. Sounds like your brushes are worn out.

 

Checked the switch, and found continuity.
However, with the truck running, there's no power at the four wires that plug into the switch (using a grounded 12V test light).
Could this mean a bad resistor?
According to the owner's manual, there's no under-dash fuse related to the a/c. I already checked the 60amp fuse under the hood.
Again, thanks.

 

Still probably the blower motor.

Go to its connector. You should have battery voltage on the orange wire whenever the ignition switch is in RUN and the HVAC MODE switch is not in OFF. With the above conditions satisfied and the connector still in place, check the orange/black wire while rotating the SPEED switch through its four positions.

If you get no voltage in any switch position, replace the blower motor. If you get something else, report back with your findings.

 

Still stumped. Orange wire in two-wire connector is hot. No voltage to other wire in any fan-speed position. Pulled the motor and bench-tested with a spare battery and jump-wires and it runs fast and smooth.
On the four-lug switch, continuity was found between the hot lug and two of the other three, but one showed nothing. Could this still be my problem?
Thanks for you advice, SHO.

 

If you did my test above exactly as written, then it's still a bad blower... The brushes are worn and, when you put it on the bench, they made contact.

The blower speed control switches the current path between the motor's "low" side and ground. In HIGH, the OR/BK wire should be connected directly to ground and will allow maximum current through the motor. In the other speed settings, various resistance values are inserted into the motor's "low" side to limit the current and the blower speed.

You might also have a bad speed switch, if it tests as described, however the voltage test I posted above indicates there is no voltage on the OR/BK wire (STILL CONNECTED!) on the "low" terminal of the motor. Therefore, there is an open circuit in the motor and it is defective.

 

I put it back together, and it's running. It failed once, though, so you're probably right. If it quits again, I'll try the new motor first.

I used to be a pretty fair mech when cars had carbs and chrome bumpers, but have always been electrically challenged.

By the way, I hear there's a new SHO (called a "Sho"?).
What do you think?

 

if the resistor were to go bad you would only have high speed working

 

Yes, Ford brought back the Taurus SHO for 2010. I've been trying to talk my daughter into buying one so I can borrow it. After all, she got to use my first 94 ATX when she was a teenager so I figure it's payback time.

 

would this be the same for the rear blower motor?