My information does not list a separate fan switch for this model; it may be part of a control assembly which would explain the high cost.
Blower Motor Speed Control The blower motor is controlled by a four-position heater blower motor switch located on the left side of the control assembly. The four positions are LOW, MEDIUM LOW, MEDIUM HIGH and HIGH. The four operating speeds are obtained with a heater blower motor switch resistor connected in series with the heater blower motor switch operating on the ground side of the blower motor.With the function control knob in the OFF position, the blower motor will not operate.With the heater blower motor switch at LOW, current flow in the ground circuit is through three resistors to obtain the lowest operating speed.With the heater blower motor switch at MEDIUM LOW, current flow in the ground circuit is through two resistors to obtain a medium low operating speed.With the heater blower motor switch at MEDIUM HIGH, current flow in the ground circuit is through one resistor to obtain a medium high operating speed.
The way it all works is as follows:
Power is supplied to the blower motor from the blower motor relay on the pink/white wire. This part of teh circuit is OK, if it works on high speed.
The ground is switched through various resistor combinations to control low speeds.
the black wirte from teh AC control assembly is the ground source for teh circuit. The AC control connects this ground to teh blower switch through the red/ orange wire to the blower switch. The blower switch then connects the ground circuit to the lg/w, y/rd wires to pass through one or 2 resistors dependinon speed selected. The orange/blk wire from the switch to the resistor bypasses the resistors and dirrectly grounds the circuit for high speed operation. There is a thermal limiter (fuse) built into the resistor block itself.
On medium speeds with everythign conencted, check for power at teh y/rd or lg/w wires at the resistor; if there is no power present there, then the resistor is probably open and likely the source of teh problem. Resistors fail much more often thatn control switches due to heat, moisture, and vibration present in the heater case.
I see the first part of my posting did not display: it was a part # XXXXX price for a resistor for your vehicle. It read as follows:
4L5Z19A706AA (front blower resistor assy) $16.45
The information provided for your vehicle does not mention which side of the veihicle any of these componets are located on; when it mentions "ground side" it is referring to the fact that the circuit is swithed on the ground side, that is in between teh load (motor) and battery negative (chassis ground) in the circuit... it doesnt refer to any particular location of components...
Do the wire colors mentioned in the procedure match the wire colors on the vehicle?
A fan switch never has 12 or 13 detents, as there are not that many wires to select in the circuit... are you sure what you are referring to as the switch is the fan switch, or is it a climate control system, where the switch is controlling more than blower speed?
From your original description of the vehicle, it is inferred that it is a manually controlled AC system; you mention having found the resistor block. If it is a climate control (automatic) system, then there is not resistor block in the system; it is microprocessor controlled and the diagnostic procedure is very different...
On an automatic system, you will need to begin by entering the self diagnostic mode and retrieving any failure codes stored in it's memory.
this is done as follows:
EATC On Board Diagnostics Test
An important diagnositc clue also:
Does the blower operate at high speed in all positions, or is it on high in high position, and off in all other positions?
If it is a thumbwheel controlled fan switch, then you have an automatically controlled system; preforming the diagnostic self test procedure as detailed in the last response should generate service codes to help diagnose the source of the failure.
What kind of test equipment do you have available to you at teh moment; do you have a DVOM, a 12 volt test light, or some other way of testing for power and ground at various poiints in the circuit?