Test E: 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 Blower Motor Switch Positions

Turn ignition to run position (engine off). Place function selector switch in FLOOR position and slowly rotate blower motor switch from LO to HI position. If blower motor only operates in HI position, replace blower motor resistor. Retest system. If blower motor operates in other than only HI position, go to next step.

Check Orange/Black, Light Green/White, Yellow/Red & Black Wire Circuits For Open

Turn ignition off. Disconnect blower motor resistor and blower motor switch connectors. With an ohmmeter, measure resistance between blower motor resistor and blower motor switch terminals. See BLOWER MOTOR RESISTOR/SWITCH RESISTANCE CHECK table. If resistances are less than 5 ohms, go to next step. If resistances are greater than 5 ohms, repair wiring as necessary.

BLOWER MOTOR RESISTOR/SWITCH RESISTANCE CHECK

Blower Motor Resistor Terminal No. (Wire Color)	Blower Motor Switch Terminal No.
2 (Orange/Black)	2
1 (Light Green/White)	3
4 (Yellow/Red)	4
3 (Black)	1

Check Orange/Black, Light Green/White & Yellow/Red Wire Circuits For Short

Measure resistance between ground and blower motor switch terminal No. 2 (Orange/Black wire), terminal No. 3 (Light Green/White wire), and terminal No. 4 (Yellow/Red wire). If resistances are greater than 10,000 ohms, go to next step. If resistances are less than 10,000 ohms, repair wiring as necessary. Retest system.

Check Blower Motor Switch

Measure resistance between blower motor switch terminals. See BLOWER MOTOR SWITCH TERMINALS RESISTANCE SPECIFICATIONS table. If continuity is as indicated in table, reconnect blower motor resistor connector and go to next step. If continuity is not as indicated in table, replace blower motor switch. Retest system.

BLOWER MOTOR SWITCH TERMINALS RESISTANCE SPECIFICATIONS

Switch Position	Continuity Between Terminals No.
LO	None
Medium-Low	2 & 3
Medium-High	2, 3 & 4
HI	1, 2 & 4

Check Blower Motor Resistor

Measure resistance between blower motor switch connector terminals. See BLOWER MOTOR SWITCH CONNECTOR TERMINALS RESISTANCE SPECIFICATIONS table. If resistances are to specification, replace blower motor. If resistances are not to specification, replace blower motor resistor.

BLOWER MOTOR SWITCH CONNECTOR TERMINALS RESISTANCE SPECIFICATIONS

Terminal No. (Wire Color)	Terminal No. (Wire Color)	Ohms
1 (Black)	2 (Orange/Black)	2.5
1 (Black)	3 (Lt. Green/White)	1.2
2 (Orange/Black)	3 (Lt. Green/White)	1.6
2 (Orange/Black)	4 (Yellow/Red)	2.2