98se blower motor

Hi, nice forum you have here. A friend has a 98 that the blower motor will not function. Removed motor hooked to 12v source and spins fine. Used multimeter to check plug for blower and get 11.5 volts, but the motor will not run. What am I missing here? And where might the heater/blower switch be?

What did you use for grounding the multimeter when you checked the voltage at the plug, a good chassis ground or the ground for the blower motor? If you used a known ground, make the measurement again using the blower motor's ground (might be in the plug, I don't have my schematic in front of me). Maybe you have a bad ground.

Does the blower motor work on high speed, just not on the slower speeds? If it does, then you probably have a bad blower motor resistor pack. High speed is battery voltage to the motor and bypasses the blower motor resistor pack. All other speeds utilize the resistors.

-Rod

What did you use for grounding the multimeter when you checked the voltage at the plug, a good chassis ground or the ground for the blower motor? If you used a known ground, make the measurement again using the blower motor's ground (might be in the plug, I don't have my schematic in front of me). Maybe you have a bad ground.

Does the blower motor work on high speed, just not on the slower speeds? If it does, then you probably have a bad blower motor resistor pack. High speed is battery voltage to the motor and bypasses the blower motor resistor pack. All other speeds utilize the resistors.

-Rod
I used no ground when reading plug. Plug had two sockets and I used my meter with a lead to both sockets. Someone said one wire might be a signal wire so I tried each side of plug to ground. I got 11.5 volts on one side nothiing on the other. Think it might be heater/blower switch, I guess this acts like a reostat to control fan speed. Now how does that dash panel come out? And no fan worked on no speeds.

I've posted the schematic for the '98 Taurus manual blower speed controls at http://www.members.aol.com/Rod2414738/Car_Stuff/blower_motor.pdf.

Since you measured battery voltage across the terminals to the blower motor, I'd suggest you check the grounds and connections through the system, especially at the blower motor switches and the blower motor resistors. Your DMM will have very high input impedance and therefore will read battery voltage even if one of the connectors is melted or corroded and so high in resistance very little current can flow through it.

If the car you are working on has the Electronic Automatic Temperature Control (EATC), then it uses a pulse width modulated blower motor speed control. If you are working with the EATC, let me know and I'll put those wiring diagrams up as well.

To get to the switch assembly, you will need either the proper tool to remove the faceplate (a couple of bent pieces of steel clothes hanger can be used in a pinch as well) and then you should find common screws holding the assembly in.

The steps for the blower motor switch are as follows according to the service manual:
1. Remove climate control assembly as described.
2. Remove knob as described.
a. Note: Do not pry the knob (18519) off its shaft. Damage to the surface of the integrated control panel may result.
b. Rotate knob to straight up-and-down position, grasp knob and pull rearward.
c. If the D-shaped spring clip which sits inside the back end of knobremains on shaft when knob is pulled off, remove it with needlenose pliers and install on knob.
d. To install knob, align its keyed surface with mating surface on shaft, rotate to straight up-and-down position and press knob forward until fully seated in control shaft.
3. Remove retaining screw.
4. Remove heater blower motor switch (18578).

-Rod

I've posted the schematic for the '98 Taurus manual blower speed controls at http://www.members.aol.com/Rod2414738/Car_Stuff/blower_motor.pdf.

Since you measured battery voltage across the terminals to the blower motor, I'd suggest you check the grounds and connections through the system, especially at the blower motor switches and the blower motor resistors. Your DMM will have very high input impedance and therefore will read battery voltage even if one of the connectors is melted or corroded and so high in resistance very little current can flow through it.

If the car you are working on has the Electronic Automatic Temperature Control (EATC), then it uses a pulse width modulated blower motor speed control. If you are working with the EATC, let me know and I'll put those wiring diagrams up as well.

To get to the switch assembly, you will need either the proper tool to remove the faceplate (a couple of bent pieces of steel clothes hanger can be used in a pinch as well) and then you should find common screws holding the assembly in.

The steps for the blower motor switch are as follows according to the service manual:
1. Remove climate control assembly as described.
2. Remove knob as described.
a. Note: Do not pry the knob (18519) off its shaft. Damage to the surface of the integrated control panel may result.
b. Rotate knob to straight up-and-down position, grasp knob and pull rearward.
c. If the D-shaped spring clip which sits inside the back end of knobremains on shaft when knob is pulled off, remove it with needlenose pliers and install on knob.
d. To install knob, align its keyed surface with mating surface on shaft, rotate to straight up-and-down position and press knob forward until fully seated in control shaft.
3. Remove retaining screw.
4. Remove heater blower motor switch (18578).

-Rod
Ok tried the blower switch, no luck. Replaced blower relay, you could see this had gotten very hot but still no blower. Just where is the resistor pack located.

I posted the instructions at http://www.members.aol.com/Rod2414738/Car_Stuff/blower_resistor.pdf

Good luck!

-Rod

I posted the instructions at http://www.members.aol.com/Rod2414738/Car_Stuff/blower_resistor.pdf

Good luck!

-Rod
Rod thanks much for all the info. the car belongs to a friend that I was trying to save money for. I told her after seeing the bad relay and melted plastic in the underhood panel that I did not feel comfortable trying to do anything with that componet. I agree a loose arching connection would case the heat needed to melt plastic. Wonder if a bad ressitor pack could cause this. She was going to take it somewhere to at least find problem. If she hasn't I will try to look at resistor pack. Assume this is a dealer item?

Ok my lady friend calls this morning, she took her car to the shop, they drove her home on the way back to shop guy tries blower. Calls her and tells her its working, all speeds and all selections(AC, Heater and Vent). They are going to look it over and call her back. Strange.