Circuit Description
This diagnostic is only for the C60 A/C system (manual control). For further diagnosis of the CJ2 system, refer to Diagnostic System Check in HVAC Systems with A/C-Automatic.
The A/C clutch relay is PCM controlled to delay A/C clutch engagement after the A/C is turned ON. This allows the PCM to adjust engine RPM before the A/C clutch engages. The PCM will engage the A/C clutch any time A/C has been requested unless any of the following conditions exist:
| • | High coolant temperature |
| • | Low A/C system pressure |
| • | High A/C system pressure |
| • | Wide open throttle |
| • | High engine RPM |
| • | Certain DTCs have been set |
When the heater and A/C control is placed in the A/C mode, a 12 volt signal is sent to the PCM. This is shown on the scan tool as A/C request YES.
When a request for A/C has been detected by the PCM, the PCM will ground the A/C clutch relay control circuit, the relay contacts will close, and current will flow through the relay to the A/C compressor clutch.
When A/C request has been detected by the PCM, the cooling fans will be turned ON when A/C pressure is above a predetermined pressure.
Diagnostic Aids
Important:
• Remove any debris from the PCM connector surfaces before servicing
the PCM. Inspect the PCM connector gaskets when diagnosing/replacing
the modules. Ensure that the gaskets are installed correctly. The
gaskets prevent contaminate intrusion into the PCM. • For any test that requires probing the PCM or a component
harness connector, use the Connector Test Adapter Kit J 35616
. Using this kit prevents damage
to the harness/component terminals. Refer to
Using Connector Test Adapters
in Wiring Systems. • Before using this table, be sure no PCM DTCs are stored. The PCM
will not activate the A/C clutch with certain DTCs set.
| • | The following may cause an intermittent: |
| - | Poor connections |
| - | Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. |
| - | Corrosion |
| - | Mis-routed harness |
| - | Rubbed through wire insulation |
| - | Broken wire inside the insulation |
| • | For an intermittent, refer to Symptoms . |
Test Description
The numbers below refer to numbers on the diagnostic table.
-
A/C DTCs will disable the A/C system. Repair A/C DTCs before proceeding.
-
The request circuit is shorted to a voltage if the scan tool displays A/C request as YES.
-
A condition exists with the request circuit between the PCM and the HVAC Programmer or the HVAC Programmer is malfunctioning if the test lamp did not illuminate. Refer to Diagnostic System Check in HVAC Systems with A/C-Manual (C60) for further diagnosis.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
Are any A/C DTCs set? | -- | Go to the applicable DTC table. | ||
Does the scan tool indicate A/C request as YES? | -- | |||
4 | Turn ON the A/C. Does the scan tool indicate A/C request as YES? | -- | System OK | |
Does the DMM display near the specified value when the A/C is enabled? | B+ | |||
6 |
Does the DMM indicate continuity? | -- | ||
7 | Probe the A/C request circuit at the PCM harness connector using the test lamp J 35616-200 connected to B+. Does the test lamp illuminate? | -- | ||
8 |
Did you find and correct the condition? | -- | System OK | |
9 |
Important: Before replacing the HVAC Programmer, refer to HVAC for further diagnosis. Replace the HVAC Programmer. Refer to Control Assembly Replacement in HVAC Systems with A/C Manual. Is the action complete? | -- | System OK | -- |
10 |
Did you find and correct the condition? | -- | System OK | |
11 | Repair the open A/C request circuit between the HVAC Programmer and the PCM. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | System OK | -- |
12 | Repair the grounded A/C request circuit between the HVAC Programmer and the PCM. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | System OK | -- |
13 |
Important: Program the replacement PCM. Replace the PCM. Refer to Powertrain Control Module Replacement . Is the action complete? | -- | System OK | -- |
