Pinpoint Test N: The Air Conditioning (A/C) Is Always On - A/C Mode Always Commanded ON
Climate Control System
Pinpoint Tests
Pinpoint Test N: The Air Conditioning (A/C) is Always On - A/C Mode Always Commanded ON
Refer to Wiring Diagram Set 54, Manual Climate Control System for schematic and connector information. Diagrams By Number
Refer to Wiring Diagram Set 55, Automatic Climate Control System for schematic and connector information. Diagrams By Number
Normal Operation
Under normal operation, for Dual Automatic Temperature Control (DATC) systems, when A/C is requested, the HVAC module - DATC sends an A/C request message over the Medium Speed Controller Area Network (MS-CAN) bus to the Instrument Cluster (IC), then from the IC through the High Speed Controller Area Network (HS-CAN) bus to the PCM.
Under normal operation, for manual climate control systems, when A/C is requested, a voltage is supplied to the PCM on the A/C request PCM input.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- PCM
- HVAC module - DATC
- Function selector switch (manual climate control systems)
PINPOINT TEST N: THE AIR CONDITIONING (A/C) IS ALWAYS ON - A/C MODE ALWAYS COMMANDED ON
NOTE: Before carrying out the following test, diagnose any HVAC, PCM or IC DTCs.
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N1 CHECK THE AIR CONDITIONING COMPRESSOR CYCLING SWITCH (ACCS) PCM PID WITH THE A/C OFF
- Enter the following diagnostic mode on the scan tool: ACCS PCM PID.
- Place the function selector switch to the OFF position or press the OFF manual override button on the HVAC module - DATC.
- Does the ACCS PCM PID read OFF?
Yes
GO to N6.
No
GO to N4.
For manual climate control systems, GO to N2.
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N2 CHECK CIRCUIT CH443 (GN/OG) FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: Climate Control Assembly C294B and C294C.
- Disconnect: PCM C175B.
- Ignition ON.
- Measure the voltage between ground and PCM 175b-15, circuit CH443 (GN/OG), harness side.
- Is any voltage present?
Yes
REPAIR circuit CH443 (GN/OG) for a short to voltage. TEST the system for normal operation.
No
GO to N3.
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N3 CHECK THE FUNCTION SELECTOR SWITCH
- Ignition OFF.
- Carry out the Function Selector Switch component test. Function Selector Switch
- Does the function selector switch test good?
Yes
GO to N5.
No
INSTALL a new function selector switch. TEST the system for normal operation.
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N4 CHECK THE AIR CONDITIONING SWITCH STATUS (AC_SEL_SW) HVAC PID WITH THE A/C OFF
- Enter the following diagnostic mode on the scan tool: AC_SEL_SW HVAC PID.
- Select PANEL mode on the HVAC module and make sure the A/C button and indicator are OFF.
- Does the AC_SEL_SW HVAC PID read Not Pressed?
Yes
GO to N6.
No
GO to N5.
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N5 CHECK THE HVAC MODULE CONNECTION
- Inspect the HVAC module connectors for:
- corrosion.
- pushed-out terminals.
- damaged terminals.
- Connect and correctly seat all the HVAC module connectors.
- Clear the DTCs.
- Operate the system and verify the concern is still present.
- Is the concern still present?
Yes
INSTALL a new HVAC module. TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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N6 CHECK THE PCM CONNECTION
- Disconnect all the PCM connectors.
- Inspect the module connectors for:
- corrosion.
- pushed-out terminals.
- damaged terminals.
- Connect and correctly seat all the PCM connectors.
- Clear the DTCs.
- Operate the system and verify the concern is still present.
- Is the concern still present?
Yes
INSTALL a new PCM. TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.
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