My 89 LX heater/ac blower motor only worked on Max. My car has the electronic climate controls - this means the fan control does not have a 1,2,3,4 setting, but allows you to control the blower from almost no fan speed, and smoothly move it up to max. I thought I'd detail how to fix this problem so that future folks with this problem won't have to do the research I did. I'll try to make this easy, but if you know nothing about electronics, give this message to a friend who does know a bit about electronics and they'll understand exactly what to do. You can fix it for less than $30.

The electronic system uses a transistor to control the fan speed. The emitter of the transistor connects to the blower fan +Voltage input (the other connector on the fan goes to ground). Therefore, if voltage appears on the transistor emitter, the fan will run. The transistor control how much voltage goes to the fan. The collector on the transistor goes to 12V and the base to a control voltage from the fan speed control.

My transistor opened up which means the fan got no voltage and would not run at all unless the fan speed control was set to max. When you do set the speed to Max, a relay shorts the collector and emitter of the transistor applying the entire 12V to the fan and making it run on Max. If your transistor shorts, you might have your fan on Max all the time - even when the control is set to a lower value.

Either way, the fix is the same - replace the transistor. There's also a resistor between the emitter and collector and you've got to replace this too.

There are three problems with this:

1. The replacement part (which consists of a little box with both the transistor and resistor inside) is $177
2. The part has been discontinued by Ford and is not available from them. You might find one at some dealer.
3. To replace it, you must remove the steering wheel, instrument console, radio and the entire dash. Cost for the dealer to do the job - at least $500.

I was not willing to try and take the whole inside of the car apart, so came up with another way.

First, you need to find the three wires that go to the transistor assembly. They are three wires - 2 thick ones and thin one that dissappear over the fan blower assembly. Both of the thick wires start at a black retangular relay on the bottom of the blower fan assembly. This is easy to see and get to.

Cut these three wires as leave them as long as you can. Since they go to the transistor and mine was open, cutting them did nothing - everthing still worked as before.

Now you need a new transistor and resistor. I bought a 2N6282 ($4.50) which is a 30 amp part. Note: this is a darlington transistor which is correct for this application. Any high current NPN darlington transistor should do. Also you need a large resistor. I used a 2 ohm 50 watt lug resistor from Ohmite ($12). I ordered both from allied electronics (www.alliedelec.com). You cannot get these at Radio Shack.

Now you need to put these somewhere. I got a metal project box from Radio Shack ($3) which is about 2X3X5. I drilled holes for the transistor and mouted it with heat sink compound to the box. The resistor mounts inside fine too. Add more holes for air circulation.

To wire it up, solder the thin wire you cut to the base of the transistor. Now use a voltmeter and check the two thick wires. One will have 12V when the fan control is turned on. Solder this one to the Collector. The other goes to the emitter. Solder the resistor lugs between the emitter and collector as well.

Now your fan control will again work normally! But you still have a couple of problems - the box will get pretty hot and there will be 12V on the entire metal surface. I also wired a small CPU fan from an old computer on the box to expel the heat, but I don't think you have to do that as mine get only warm when mounted as I'll detail.

I painted the box with black engine enamel which is not conductive. Now a slight touch with something going to ground won't blow a fuse.

Mounting was a problem. There's not room to hit it behind the cover you remove to get to the fan blower. Instead, I drilled holes in this cover and mounted the box at the back left of the passenger footwell and hanging down from the cover. I used nylon bolts and nuts from Ace Hardware to mount it to the footwell cover and it's right near the center console and in the back. You can hardly see it and feet won't hit it. It's about 3/4 inch below the cover so there's air circulation all around it.

Actually this job is easy except for controlling the heat from the parts. The original part is mounted so that the fan air blows across it to keep it cool, so we have to do something else unless you like taking out your dash.

I hope this helps someone in the future.