Blower Control

Prior to performing any diagnosis, perform Functional Tests and determine that voltage is reaching blower control by testing with voltmeter at pins 2 and 3 (both a 5 pin and a 2 pin connector are used on each unit).

BLOWER INOPERATIVE AT "65" SETTING

1. Bring engine to normal operating temperature and shut "OFF." With engine "OFF," but ignition switch "ON," LEDs should be lit for temperature and mode settings. With connector still attached to blower control, connect a suitable voltmeter to pins 1 and 7 of blower control. If voltage reading is above 3 volts, go to step 2. If voltage reading is less than 3 volts, proceed to step 3.
2. Connect voltmeter between pin 6 (blower feed) and pin 7 (ground), leaving connector attached. If 3 or more volts is indicated, blower motor is improperly grounded, or defective. If less than 3 volts is indicated, blower control is defective.
3. Connect a voltmeter at control panel (pin B of 8 pin connector) and suitable ground. If less than 3 volts is indicated, control panel is defective. If voltage fluctuates above 3 volt level, check circuit continuity. Correct as needed.

BLOWER INOPERATIVE AT "85" SETTING

1. Bring engine to normal operating temperature and shut "OFF." With engine "OFF," but ignition switch "ON," LEDs should be lit for temperature and mode settings. System must be left "ON" for at least 3 minutes prior to testing to avoid blower delay. Set temperature for "65." If blower operates, proceed to step 2. If blower does not operate, refer to Blower Inoperative At "65°" Setting for diagnosis.
2. Inspect terminal connections for blower and A/C clutch control. Check for good contact. If blower operates, clean contacts and reconnect. If blower continues to be inoperative, delay timer is defective and control panel must be replaced.

BLOWER INOPERATIVE AT "LO" SETTING

1. Bring engine to normal operating temperature and shut "OFF." With engine "OFF," but ignition switch "ON," LEDs should be lit for temperature and mode settings.
2. Connect a suitable voltmeter to blower pins 1 and 7. If voltage reading is between 3 and 7 volts and fluctuating, replace blower control. If voltage reading is above 7 volts and fluctuating, replace control panel.

HIGH BLOWER INOPERATIVE AT "HIGH" OR "DEFROST" SETTING

1. Bring engine to normal operating temperature and shut "OFF." With engine "OFF," but ignition "ON," LEDs should be lit for temperature and mode settings. Connect a suitable voltmeter to blower pins 1 and 7. If voltage reading is between 3 and 7 volts and fluctuating, replace control panel. If voltage reading is above 7 volts and fluctuating, proceed to step 2.
2. Connect voltmeter between blower pins 6 and 7. If 11 or 14 volts are measured, replace blower motor. If voltage reading is less than 10 volts, replace blower control.

NO BLOWER SPEED VARIATION AT "ECONOMY," "AUTO," "HEAT" OR "BI-LEVEL" SETTINGS

1. Bring engine to normal operating temperature and shut "OFF." Perform diagnosis with engine "OFF," but ignition "ON." Connect suitable voltmeter to blower control pin 1 and ground. Set temperature for "65," then set for "85," and "AUTO." Observe voltage readings.
a. Voltage reading should fluctuate just above 7 volts, then drop below 7 volts, and return to just above 7 volts. If so, proceed to step 2.
b. If no voltage fluctuation is indicated, control panel is defective. Replace control panel.
2. Connect voltmeter to blower control pin 6 and ground. Set temperature for "65," then set for "85," and "AUTO." Observe voltage readings.
a. If voltage reading changes from 12 volts to 3 volts, and then returns to 12 volts, blower motor is defective and must be replaced.
b. If no voltage change is indicated, blower control is defective and must be replaced.