Diagnostic Test

WARNING: This page is about a different car, the 2008 Dodge Magnum, 2008 Dodge Charger, and 2008 Chrysler 300. However, it is still accessible from the selected car via links, so may be relevant.

CHECK THE BLOWER SPEED SETTING
Was the blower control set to high speed before executing the Cooldown Test?

Yes
1. Go To step 2.
No
1. Start the engine, set the blower control to high speed, and then run the Cooldown Test again.
2. Perform BODY VERIFICATION TEST - VER 1 .
CHECK THE (C850) BLOWER SWITCH POSITION SIGNAL CIRCUIT FOR A SHORT TO THE (Z908) GROUND CIRCUIT

Fig 1: Checking Blower Switch Position Signal Circuit For Short To Ground
Courtesy of CHRYSLER LLC

Turn the ignition off.

Disconnect the A/C Heater Control C3 harness connector.

Measure the resistance between the (C850) Blower Switch Position Signal circuit and the (Z908) Ground circuit in the A/C Heater Control C3 harness connector.

Is the resistance below 10K ohms?

Yes
1. Repair the (C850) Blower Switch Position Signal circuit for a short to the (Z908) Ground circuit. Run the Cooldown Test again after the repair is complete.
2. Perform BODY VERIFICATION TEST - VER 1 .
No
1. Go To step 3.
CHECK THE (C850) BLOWER SWITCH POSITION SIGNAL CIRCUIT FOR A SHORT TO THE (Z909) GROUND CIRCUIT

Fig 2: Measuring Resistance Between Blower Switch Position Signal & Ground Circuits
Courtesy of CHRYSLER LLC

Disconnect the A/C Heater Control C1 harness connector.

Measure the resistance between the (C850) Blower Switch Position Signal circuit and the (Z909) Ground circuit in the A/C Heater Control C1 harness connector.

Is the resistance below 10K ohms?

Yes
1. Repair the (C850) Blower Switch Position Signal circuit for a short to the (Z909) Ground circuit. Run the Cooldown Test again after the repair is complete.
2. Perform BODY VERIFICATION TEST - VER 1 .
No
1. Go To step 4.
CHECK THE (C850) BLOWER SWITCH POSITION SIGNAL CIRCUIT VOLTAGE

Fig 3: Checking Blower Switch Position Signal Circuit Voltage
Courtesy of CHRYSLER LLC

Reconnect the A/C Heater Control C1 harness connector.

Turn the ignition on.

Measure the voltage of the (C850) Blower Switch Position Signal circuit.

Is the voltage above 4.8 volts?

Yes
1. Check the blower motor and related circuits for the cause of blower operation problems and repair as necessary. Run the Cooldown Test again after the repair is complete.
2. Perform BODY VERIFICATION TEST - VER 1 .
No
1. Go To step 5.
CHECK THE (C850) BLOWER SWITCH POSITION SIGNAL CIRCUIT FOR A SHORT TO GROUND

Fig 4: Checking Blower Switch Position Signal Circuit For Short To Ground
Courtesy of CHRYSLER LLC

Measure the resistance of the (C850) Blower Switch Position Signal circuit between ground and the A/C Heater Control C3 harness connector.

Is the resistance below 10K ohms?

Yes
1. Repair the (C850) Blower Switch Position Signal circuit for a short to ground. Run the Cooldown Test again after the repair is complete.
2. Perform BODY VERIFICATION TEST - VER 1 .
No
1. Go To step 6.
CHECK (C850) BLOWER SWITCH POSITION SIGNAL CIRCUIT FOR AN OPEN

Fig 5: Checking Blower Switch Position Signal Circuit For An Open
Courtesy of CHRYSLER LLC

Measure the resistance of the (C850) Blower Switch Position Signal circuit between the A/C Heater Control C1 harness connector and the A/C Heater Control C3 harness connector.

Is the resistance below 5.0 ohms?

Yes
1. Replace the A/C Heater Control in accordance with the Service Information. Run the Cooldown Test again after the repair is complete.
2. Perform BODY VERIFICATION TEST - VER 1 .
No
1. Repair the (C850) Blower Switch Position Signal circuit for an open. Run the Cooldown Test again after the repair is complete.
2. Perform BODY VERIFICATION TEST - VER 1 .