Diagnostic Procedure

WARNING: This page is about a different car, the 2004 Dodge Pickup and 2004 Dodge Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Refer to VERIFICATION TESTS for appropriate verification test procedures.

Ignition on, engine not running.
Verify that communication with the HVAC and PCM is available over the BUS.

With the DRBIII®, check for DTCs in the PCM and HVAC module.

Are any A/C DTCs or communication failures present?
1. Yes --> Diagnose the related DTC(s) or BUS failure before continuing.
  Perform POWERTRAIN VERIFICATION TEST VER - 2 .
2. No --> Go To 2
Engine running.
With the DRBIII®, read the A/C Select status in the PCM.

Turn the A/C Switch on and off a few times.

Does the A/C Select state change?
1. Yes --> Go To 3
2. No --> Go To 12
Engine Running.
Turn the A/C system on and the fan on high.

With the DRBIII® in Inputs/Outputs, read the A/C request state.

Does the A/C request state change?
1. Yes --> Go To 4
2. No --> Repair the open in the A/C Request circuit.
  Perform POWERTRAIN VERIFICATION TEST VER - 2 .
Turn the ignition off.
Verify that the Refrigerant System is properly charged per Service Procedure.

Is the Refrigerant System properly charged?
1. Yes --> Go To 5
2. No --> Properly charge the Refrigerant System per Service Information.
  Perform POWERTRAIN VERIFICATION TEST VER - 2 .
Verify the High Pressure Cut-Off Switch operation per Service Information.
Is the High Pressure Cut-Off Switch OK?
1. Yes --> Go To 6
2. No --> Replace the High Pressure Cut-Off Switch.
  Perform POWERTRAIN VERIFICATION TEST VER - 2 .
Verify the Low Pressure Switch operation per Service Information.
Is the Low Pressure Switch OK?
1. Yes --> Go To 7
2. No --> Replace the Low Pressure Switch.
  Perform POWERTRAIN VERIFICATION TEST VER - 2 .
Ignition on, engine not running.
Disconnect the A/C Compressor Clutch harness connector.

Connect a test light between the ground circuit and the A/C Clutch Relay Output circuit.

With the DRBIII®, actuate the A/C Clutch Relay.

Does the test light illuminate brightly on and off with the relay actuation?
1. Yes --> Replace the A/C Clutch Coil.
  Perform POWERTRAIN VERIFICATION TEST VER - 2 .
2. No --> Go To 8
Turn the ignition off.
Disconnect the A/C Clutch harness connector.

NOTE: Check connectors - Clean/repair as necessary.

Measure the resistance between ground and the A/C Compressor Clutch ground circuit in the A/C Clutch harness connector.

Is the resistance below 5.0 ohms?
1. Yes --> Go To 9
2. No --> Repair the open in the A/C Compressor Clutch ground circuit.
  Perform POWERTRAIN VERIFICATION TEST VER - 2 .
Remove the A/C Clutch Relay.
Measure the resistance of the (C3) A/C Clutch Relay Output circuit between the IPM and the A/C Clutch Coil.

Is the resistance below 5.0 ohms?
1. Yes --> Go To 10
2. No --> Repair the open in the (C3) A/C Clutch Relay Output circuit.
  Perform POWERTRAIN VERIFICATION TEST VER - 2 .
Measure the voltage of the Fused B+ circuit at the A/C Clutch Relay connector.
Is the voltage above 11.0 volts?
1. Yes --> Go To 11
2. No --> Repair the open in the Fused B+ circuit. The open may be in the IMP.
  Perform POWERTRAIN VERIFICATION TEST VER - 2 .
If there are no possible causes remaining, view repair.
1. Repair
  1. Replace the A/C Clutch Relay.
  2. Perform POWERTRAIN VERIFICATION TEST VER - 2 .
Ignition on, engine not running.
With the DRBIII® in the HVAC, under the Monitors screen, read the A/C Select Switch state.

While monitoring the DRBIII® screen, turn the A/C switch on and off a few times.

Does the A/C Select State change on the HVAC Monitors screen.
1. Yes --> Check for any related TSBs. Replace and program the PCM in accordance with the Service Information as long as no BUS problems exist.
  Perform POWERTRAIN VERIFICATION TEST VER - 2 .
2. No --> Replace the A/C-Heater Control module.
  Perform POWERTRAIN VERIFICATION TEST VER - 2 .