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Climate Control Pinpoint Test 10: No Operation In Lower Speeds

CLIMATE CONTROL PINPOINT TEST 10 CHART - NO OPERATION IN LOWER SPEEDS

PINPOINT TEST 10 NO OPERATION IN LOWER SPEEDS
STEP INSPECTION ACTION
1 CHECK CIRCUIT (O/B) WIRE FOR AN OPEN
  • Disconnect blower motor resistor connector 0740-105.
  • Key ON.
  • Turn the A/C mode switch to the FLOOR position.
  • Measure the voltage between the blower motor resistor connector 0740-105 pin 4 (O/B) and ground.
  • Is the voltage greater than 10 volts? 
 Yes Go to step 2.
No Repair circuit (O/B) for a open circuit between the blower motor and the blower motor resistor. Test the system for normal operation.
2 CHECK CIRCUIT (R/O) FOR AN OPEN
  • Key OFF.
  • Measure the resistance between the blower motor resistor connector 0740-105 pin 2 (R/O) and ground.
  • Is the resistance less than 5 ohms? 
 Yes Go to step 3.
No Repair circuit (R/O) for an open circuit between the blower motor resistor and the splice. Test the system for normal operation.
3 CHECK MEDIUM/LOW BLOWER CIRCUIT (LG/W)
  • Turn the blower motor switch to the medium/low position.
  • Measure the resistance between the blower motor resistor connector 0740-105 pin 1 (LG/W) wire and ground.
  • Is the resistance less than 5 ohms? 
 Yes Go to step 4.
No Go to step 6.
4 CHECK MEDIUM/HIGH BLOWER CIRCUIT (Y/R)
  • Turn the blower motor switch to the medium/high position.
  • Measure the resistance between the blower motor resistor connector 0740-105 pin 3 (Y/R) and ground.
  • Is the resistance less than 5 ohms? 
 Yes Replace the blower motor resistor.
No Go to step 5.
5 CHECK CIRCUIT (Y/R) FOR AN OPEN
  • Disconnect the function selector switch 0740-102.
  • Measure the resistance between blower motor resistor connector 0740-105 pin 3 (Y/R) and the function selector switch connector 0740-102 pin 4 (Y/R).
  • Is the resistance less than 5 ohms? 
 Yes Replace the blower motor switch. See HEATER CONTROL SWITCH REMOVAL / INSTALLATION . Test the system for normal operation.
No Repair circuit (Y/R) for an open. Test the system for normal operation.
6 CHECK CIRCUIT (LG/W) FOR AN OPEN
  • Disconnect the function selector switch 0740-102.
  • Measure the resistance between the blower motor resistor connector 0740-105 pin 1 (LG/W) and the function selector switch connector 0740-102 pin 2 (B).
  • Is the resistance less than 5 ohms? 
 Yes Replace the blower motor switch. See HEATER CONTROL SWITCH REMOVAL / INSTALLATION . Test the system for normal operation.
No Repair circuit (LG/W) for an open. Test the system for normal operation.
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