Dodge Ram Truck 1500-2500-3500. Manual — part 1274

*CHECKING A/C SYSTEM OPERATION WITH NO DTCS

9 - 2018

ENGINE - ELECTRICAL DIAGNOSTICS - SRT-10

DR/DH

*CHECKING A/C SYSTEM OPERATION WITH NO DTCS (CONTINUED)

For the XXXX circuit diagram (Refer to 9 - ENGINE - SCHEMATICS AND DIAGRAMS).

For a complete wiring diagram Refer to Section 8W.

Possible Causes

A/C SELECT CIRCUIT OPEN

A/C SELECT IN HVAC

PCM

A/C REQUEST CIRCUIT OPEN

REFRIGERATION SYSTEM NOT PROPERLY CHARGED

HIGH PRESS CUT-OFF SWITCH

LOW PRESSURE SWITCH

A/C CLUTCH COIL

A/C COMPRESSOR CLUTCH GROUND CIRCUIT OPEN

(C3) A/C CLUTCH RELAY OUTPUT CIRCUIT OPEN

FUSED B+ CIRCUIT OPEN

A/C CLUTCH RELAY

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)

Diagnostic Test

1.

DTC AND COMMUNICATION PRESENT

Ignition on, engine not running.

Verify that communication with the HVAC and PCM is available over the BUS.

With the scan tool, check for DTCs in the PCM and HVAC module.

Are any A/C DTC’s or communication failures present?

Yes

>> Diagnose the related DTC(s) or BUS failure before continuing.

Perform BODY VERIFICATION TEST - VER 1.

No

>> Go To 2

2.

A/C SELECT CIRCUIT OPEN

Engine running.

With the scan tool, 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?

Yes

>> Go To 3

No

>> Go To 12

DR/DH

ENGINE - ELECTRICAL DIAGNOSTICS - SRT-10

9 - 2019

*CHECKING A/C SYSTEM OPERATION WITH NO DTCS (CONTINUED)

3.

A/C REQUEST CIRCUIT OPEN

Engine Running.

Turn the A/C system on and the fan on high.

With the scan tool in Inputs/Outputs, read the A/C request state.

Does the A/C request state change?

Yes

>> Go To 4

No

>> Repair the open in the A/C Request circuit.

Perform BODY VERIFICATION TEST - VER 1.

4.

REFRIGERATION SYSTEM NOT PROPERLY CHARGED

Turn the ignition off.

Verify that the Refrigerant System is properly charged per Service Procedure.

Is the Refrigerant System properly charged?

Yes

>> Go To 5

No

>> Properly charge the Refrigerant System per Service Information.

Perform BODY VERIFICATION TEST - VER 1.

5.

HIGH PRESSURE CUT-OFF SWITCH

Turn the ignition off.

Verify the High Pressure Cut-Off Switch operation per Service Information.

Is the High Pressure Cut-Off Switch OK?

Yes

>> Go To 6

No

>> Replace the High Pressure Cut-Off Switch.

Perform BODY VERIFICATION TEST - VER 1.

6.

LOW PRESSURE SWITCH

Turn the ignition off.

Verify the Low Pressure Switch operation per Service Information.

Is the Low Pressure Switch OK?

Yes

>> Go To 7

No

>> Replace the Low Pressure Switch.

Perform BODY VERIFICATION TEST - VER 1.

7.

A/C CLUTCH COIL

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 scan tool, actuate the A/C Clutch Relay.

Does the test light illuminate brightly on and off with the relay actuation?

Yes

>> Replace the A/C Clutch Coil.

Perform BODY VERIFICATION TEST - VER 1.

No

>> Go To 8

9 - 2020

ENGINE - ELECTRICAL DIAGNOSTICS - SRT-10

DR/DH

*CHECKING A/C SYSTEM OPERATION WITH NO DTCS (CONTINUED)

8.

A/C COMPRESSOR CLUTCH GROUND CIRCUIT OPEN

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?

Yes

>> Go To 9

No

>> Repair the open in the A/C Compressor Clutch ground circuit.

Perform BODY VERIFICATION TEST - VER 1.

9.

(C3) A/C CLUTCH RELAY OUTPUT CIRCUIT OPEN

Turn the ignition off.

Disconnect the A/C Clutch harness connector.

Remove the A/C Clutch Relay.

NOTE: Check connectors - Clean/repair as necessary.
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?

Yes

>> Go To 10

No

>> Repair the open in the (C3) A/C Clutch Relay Output circuit.

Perform BODY VERIFICATION TEST - VER 1.

10.

(A17) FUSED B+ CIRCUIT OPEN

Turn the ignition off.

Remove the A/C Clutch Relay.

NOTE: Check connectors - Clean/repair as necessary.
Measure the voltage of the Fused B+ circuit at the A/C Clutch Relay connector.

Is the voltage above 11.0 volts?

Yes

>> Go To 11

No

>> Repair the open in the Fused B+ circuit. The open may be in the IMP.

Perform BODY VERIFICATION TEST - VER 1.

11.

A/C CLUTCH RELAY

If there are no possible causes remaining, view repair.

Repair

Replace the A/C Clutch Relay.

Perform BODY VERIFICATION TEST - VER 1.

DR/DH

ENGINE - ELECTRICAL DIAGNOSTICS - SRT-10

9 - 2021