blower switch

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Oct 27, 2006 | 07:24 PM

k150

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blower switch

Speed switch for heater has only 2 speeds out of 4. seems like lo is #2 and 2,3 and hi are all the same. Could it be the switch the motor or something else? Thanks.

Oct 27, 2006 | 09:00 PM

Franklin2

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From: Virginia

Probably not the motor. I do not have any manuals on your year(if you are working on the 97) but the earlier years used a resistor network mounted in the air duct to make the motor go faster or slower. The switch selected which resistor was inline with the motor.

Oct 28, 2006 | 11:46 AM

k150

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Ok thanks any idea where the resistor is located and how I can get to it?

Oct 28, 2006 | 06:59 PM

k150

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And yes it is a 97 150

Oct 28, 2006 | 08:11 PM

Franklin2

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From: Virginia

I have a 99 diagram, and it does still have the resistor network. The location of the resistor is not very descriptive in the diagram though. They say the resistor is near the blower motor. The blower motor is on the right side of the engine compartment. I assumed you had A/C.

If you find the blower motor, start looking for a plug with 4 wires going to it. If it's like the older trucks, it will look like the plug is going to a little circuit board screwed into the duct. If you take the circuit board out, you will find little coils of wire on the other side. These are the resistors, and are placed in the air flow of the blower because they get very hot.

See if the plug is corroded, and also check to see if any of the coils are burned out or touching each other.

Oct 29, 2006 | 07:30 AM

k150

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Thanks Dave, I'll look at it today.

Oct 29, 2006 | 12:59 PM

k150

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Well that was a good start, the blower motor is under the dash behind the glove box, looks to be a squirrel cage. Next to the blower is a square plug that has 4 wires, there is a factory tag on the wires that says AC and has 2 screws next to it.Remove the screws and it drops out. the unit has 3 springs(coils) and a ?diode? ,mine is all rusted. I'll try to find one tomorrow.
Thanks again Dave.