Test M: Auxiliary Blower Motor Does Not Operate Properly
WARNING: This page is about a different car, the 1999 Ford Expedition. However, it is still accessible from the selected car via links, so may be relevant.
- Check Auxiliary Blower Motor Resistor Thermal Limiter
Turn ignition off. Disconnect auxiliary blower motor resistor. Measure resistance between auxiliary blower motor resistor terminals No. 2 (Red/Pink wire) and 3 (Orange/Red wire). Resistance should be 5.5-8.5 ohms. Measure resistance between terminals No. 1 (Light Blue/Orange wire) and 3. Resistance should be 2.5-4.0 ohms. Measure resistance between terminals No. 3 and 4 (Dark Blue/White wire). Resistance should be .5-.7 ohms. If all resistances are correct, go to next step. If any resistance is incorrect, replace auxiliary blower motor resistor. Retest system. - Check Voltage To Auxiliary Blower Motor Resistor
Turn ignition to run (engine off). Place function selector in MAX A/C position. Place front auxiliary blower motor switch in OFF position. Place rear auxiliary blower motor switch in OFF position. Measure voltage of Orange/Red wire between auxiliary blower motor resistor connector and ground. If voltage is more than 10 volts, go to step 5) . If voltage is less than 10 volts, go to next step. - Check Orange/Red Wire Circuit For Open
Turn ignition off. Measure resistance of Orange/Red wire between auxiliary blower motor resistor and ground. If resistance is more than 10,000 ohms, go to next step. If resistance is less than 10,000 ohms, repair open in Orange/Red wire. Retest system. - Check Orange/Red Wire Circuit For Short
Disconnect front auxiliary blower motor switch connector. Measure resistance of Orange/Red wire between auxiliary blower motor resistor and ground. If resistance is more than 10,000 ohms, replace front auxiliary blower motor switch. Retest system. If resistance is less than 10,000 ohms, repair Orange/Red wire. - Check Voltage To Front Auxiliary Blower Motor Switch
Turn ignition off. Disconnect front auxiliary blower motor switch connector. Turn ignition to run (engine off). Place function selector in MAX A/C position. Measure voltage of Orange/Red wire between front auxiliary blower motor switch connector and ground. If voltage is more than 10 volts, go to next step. If voltage is less than 10 volts, repair Orange/Red wire. Retest system. - Check Dark Blue/White Wire Circuit
Measure resistance of Dark Blue/White wire between auxiliary blower motor resistor and front auxiliary blower motor switch. Measure resistance of Dark Blue/White wire between auxiliary blower motor resistor and ground. If resistance is less than 5 ohms between connectors and more than 10,000 between connector and ground, go to next step. If resistance is not as specified, repair Dark Blue/White wire. Retest system. - Check Light Blue/Orange Wire Circuit
Measure resistance of Light Blue/Orange wire between auxiliary blower motor resistor and front auxiliary blower motor switch. Measure resistance of Light Blue/Orange wire between auxiliary blower motor resistor and ground. If resistance is less than 5 ohms between connectors and more than 10,000 between connector and ground, go to next step. If resistance is not as specified, repair Light Blue/Orange wire. Retest system. - Check Red/Pink Wire Circuit
Measure resistance of Red/Pink wire circuit between auxiliary blower motor resistor connector and ground. If resistance is greater than 10,000 ohms, go to next step. If resistance is less than 10,000 ohms, repair Red/Pink wire. Retest system. - Check Black/White Wire Circuit
Measure resistance of Black/White wire circuit between auxiliary blower motor switch connector and ground. If resistance is greater than 10,000 ohms, replace front auxiliary blower motor switch. Retest system. If resistance is less than 10,000 ohms, repair Black/White wire. Retest system.