1998 Ford Explorer blower motor

LCTOM7

MEMBER
1998 FORD EXPLORER
6 CYL
4WD
AUTOMATIC
130,000 MILES

I have replaced the interior switch for the heater blower, the relay for the blower, and the blower motor. My heater/AC blower still only runs on medium high and high. Why can't I get the blower to run on low and medium low?

Saturday, January 3rd, 2009 AT 8:47 PM

1 Reply

DAVE H

MECHANIC
13,384 POSTS

TEST H: BLOWER MOTOR DOES NOT OPERATE PROPERLY
Check Blower Motor Low Speed Operation

Turn ignition to run position (engine off). Place function selector switch to FLOOR position. Place blower motor switch in low position. If blower motor operates, go to step 5). If blower does not operate, go to next step.
Check Blower Medium-Low Speed Operation

Turn blower motor switch to medium-low speed position. If blower motor operates at medium-low speed, go to step 4). If blower motor does not operate, go to next step.
Check Yellow/Red Wire For Open

Disconnect blower motor switch. Disconnect blower motor resistor. Measure resistance of Yellow/Red wire between blower motor switch connector terminal No. 4 and blower motor resistor connector terminal No. 3. See Fig. 4. If resistance is less than 5 ohms, go to next step. If resistance is greater than 5 ohms, locate and repair open in Yellow/Red wire. Retest system.
Check Blower Medium/High Speed Operation

Turn blower motor switch to medium/high position. If blower motor operates at medium/high speed, go to step 6). If blower motor does not operate, go to next step.
Check Light Green/White Wire For Open

Disconnect blower motor switch. Disconnect blower motor resistor. Measure resistance of Light Green/White wire between blower motor switch connector terminal No. 3 and blower motor resistor connector terminal No. 1. See Fig. 4. If resistance is less than 5 ohms, go to next step. If resistance is greater than 5 ohms, locate and repair open in Light Green/White wire. Retest system.
Check High Speed Blower Motor Relay For Voltage

Disconnect high speed blower motor relay. With a voltmeter, measure voltage between high speed blower motor relay connector terminals No. 87 (Orange/Black wire) and No. 86 (Pink/White wire). See Fig. 5. If voltage is greater than 10 volts, replace high speed blower motor relay. If voltage is less than 10 volts, go to next step.
Check A/C Blower Motor Resistor

Zero DVOM by touching leads together and record resistance value. Measure resistance between A/C blower motor resistor terminals No. 2 and 4. See Fig. 6. Subtract resistance value recorded when zeroing DVOM. If resistance value is 3.375-4.125 ohms, go to next step. If reading is not as specified, replace blower motor resistor. Retest system.
Check Red/Orange Wire For Open

Turn function selector switch to MAX A/C. Measure resistance of Red/Orange wire between blower motor resistor connector terminal No. 2 and ground. See Fig. 4. If resistance is less than 5 ohms, go to next step. If resistance is greater than 5 ohms, repair open in Red/Orange wire. Retest system.
Check Blower Motor Switch

Turn ignition off. Disconnect blower motor switch. Measure resistance between blower motor switch terminals. See BLOWER MOTOR SWITCH CONTINUITY TEST table. If resistance is less than 5 ohms between specified terminals, repair Orange/Black wire. Retest system. If resistance is not as specified, replace blower motor switch. Retest system.
BLOWER MOTOR SWITCH CONTINUITY TEST
Switch Position. Continuity Between Terminal No.
Low. None
Medium-Low.2 & 3
Medium-High.2, 3 & 4
High.1, 2 & 4