1994 Ford Thunderbird blower motor

Tiny
JRJ94
  • MEMBER
  • 1994 FORD THUNDERBIRD
Heater problem
1994 Ford Thunderbird V8 Two Wheel Drive Automatic

blower motor not working in any mode. Fuses good. Car has climate control.
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Thursday, February 19th, 2009 AT 10:11 AM

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Tiny
DAVE H
  • EXPERT
HEATER BLOWER MOTOR INOPERATIVE
Voltage Supply Remove A/C-heater switch. Turn ignition on. Connect test light to ground. Probe A/C-heater control connector terminal No. 3 (Brown/Orange wire). If test light comes on, go to step 4). If test light does not come on, go to next step.
Voltage Supply Circuit Voltage Using test light, probe output side of fuse No. 9 (15-amp). If test light comes on, check for open in Brown/Orange wire. Repair wire as necessary. Connect A/C-heater switch connector. Test system operation. If test light does not come on, go to next step.
Brown/Orange Wire Short Circuit Remove fuse No. 9 (15-amp). Unplug A/C-heater control connector. Connect ohmmeter to ground and Brown/Orange wire at A/C-heater switch connector. If resistance is 5 ohms or less, check for open in Brown/Orange wire. Repair wire as necessary. If resistance is greater than 5 ohms, replace fuse No. 9 and go to next step.
A/C-Heater Switch, Blower Output Unplug A/C-heater blower motor connector. Reconnect A/C-heater switch connector. Actuate A/C-heater switch to any position except OFF. Using a test light, probe connector terminal No. 1 (Dark Blue/Light Green wire). If test light comes on, go to next step. If test light does not come on, replace A/C-heater switch. Retest A/C-heater system.
Dark Blue/Light Green Wire Open Circuit Actuate A/C-heater switch to any position except OFF. Using a test light, probe Dark Blue/Light Green wire at motor connector. If test light comes on, go to next step. If test light does not come on, check for open in Dark Blue/Light Green wire. Repair wire as necessary. Connect all components and retest system.
Blower Motor Operation Reconnect blower motor connector. Using jumper wire, connect battery negative terminal to Black wire at blower motor connector. If blower motor operates, go to next step. If blower motor does not operate, replace blower motor.
Orange/Black Wire Disconnect blower motor, blower motor resistor and blower motor switch. Using an ohmmeter, check resistance in Orange/Black wire between blower motor connector and resistor connector. If resistance is 5 ohms or less, go to next step. If resistance is greater than 5 ohms, check for open in Orange/Black wire. Repair wire as necessary. Retest system.
Orange/Black Wire At Switch Reconnect resistor connector. Using an ohmmeter, check resistance in Orange/Black wire between blower motor connector and blower motor switch connector. If resistance is 5 ohms or less, go to next step. If resistance is greater than 5 ohms, check for open in Orange/Black wire. Repair wire as necessary. Retest system.
Light Green/White Wire Using an ohmmeter, check resistance in Light Green/White wire between blower motor switch and blower motor resistor. If resistance is 5 ohms or less, go to next step. If resistance is greater than 5 ohms, check for open in Light Green/White wire. Repair wire as necessary. Retest system.
Yellow/Red Wire Using an ohmmeter, check resistance in Yellow/Red wire between blower motor switch and blower motor. If resistance is 5 ohms or less, go to next step. If resistance is greater than 5 ohms, check for open in Yellow/Red wire. Repair wire as necessary. Retest system.
Black Wire Ground Connect one ohmmeter lead to ground. Connect remaining lead to Black wire at blower motor switch. If resistance is 5 ohms or less, go to next step. If resistance is greater than 5 ohms, check for open in Black wire. Repair wire as necessary. Retest system.
Black Wire Ground At Resistor Connect one ohmmeter lead to ground. Connect remaining lead to Black wire at blower motor resistor. If resistance is 5 ohms or less, go to next step. If resistance is greater than 5 ohms, check for open in Black wire. Repair wire as necessary. Retest system.
A/C-Heater Blower Motor Resistor Remove blower motor resistor. Visually inspect coils for damage. Replace resistor, if defective. Using an ohmmeter, check all resistor terminals for continuity. Check thermal limiter for continuity. If continuity exists at all terminals, go to next step. If continuity does not exist at all terminals, replace blower motor resistor. Retest system.
Blower Motor Switch Using a self-powered test light or ohmmeter, check blower motor switch continuity as indicated. See BLOWER MOTOR SWITCH TEST table. Replace switch if continuity is not as specified.
BLOWER MOTOR SWITCH TEST
Speed & Switch Position. Circuit Continuity
Medium-Low (1)
LO. Open
Medium 1. Closed
Medium 2. Open
HI. Open
Medium-High (2)
LO. Open
Medium 1. Open
Medium 2. Closed
HI. Open
High (3)
LO. Open
Medium 1. Open
Medium 2. Open
HI. Closed
(1)Measured between Orange/Black wire and Light Green/White wire.
(2)Measured between Orange/Black wire and Yellow/Red wire.
(3)Measured between Orange/Black wire and Black wire.
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Thursday, February 19th, 2009 AT 10:25 AM

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