Diagnostic Test

WARNING: This page is about a different car, the 2005 Jeep Grand Cherokee. However, it is still accessible from the selected car via links, so may be relevant.

1) CHECK THE (C255) LEFT BLEND DOOR DRIVER CIRCUIT & THE (C55) LEFT BLEND DOOR COMMON DRIVER CIRCUIT FOR A SHORT TO VOLTAGE

Fig 1: Checking Left Blend Door Driver Circuit & Left Blend Door Common Driver Circuit For Short To Voltage
Courtesy of DAIMLERCHRYSLER CORP.

Turn the ignition off.

Disconnect the A/C Heater Control C2 harness connector.

Turn the ignition on.

Measure the voltage of the (C255) Left Blend Door Driver circuit.

Measure the voltage of the (C55) Left Blend Door Common Driver circuit.

Is the voltage above 0.2 volts on either circuit?

Yes
1. Repair the circuit(s) with voltage above 0.2 volts a short to voltage.
2. Perform BODY VERIFICATION TEST - VER 1 .
No
1. Go To step 2).
2) RUN THE ACTUATOR DTC DETECTION TEST
Turn the ignition off.

Reconnect the A/C Heater Control C2 harness connector.

Turn the ignition on.

With the scan tool, erase HVAC DTCs.

Turn the ignition off, wait 10 seconds, and then turn the ignition on.

With the scan tool, select System Tests and then select Actuator DTC Detection. When the test is complete, select View DTCs.

Does the scan tool only display: B10A4-LEFT BLEND DOOR CONTROL CIRCUIT HIGH (ATC)?

Yes
1. Replace the A/C Heater Control in accordance with the Service Information.
2. Perform BODY VERIFICATION TEST - VER 1 .
No, Other DTC(s) Displayed
1. Diagnose and repair the other DTC(s). If multiple DTCs are present, diagnose and repair all short high DTCs before diagnosing short low DTCs. Refer to the DIAGNOSTIC CODE INDEX for a complete list of all HVAC related symptoms.
No, And No Other DTCs Displayed
1. Using the wiring diagram as a guide, inspect the wiring and connectors for conditions causing an intermittent short. Repair as necessary.
2. Perform BODY VERIFICATION TEST - VER 1 .