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, when A/C is requested, in the Dual Automatic Temperature Control (DATC) system, a message is sent over the Medium Speed Controller Area Network (MS-CAN) bus from the HVAC module - DATC 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, when A/C is requested, in the Electronic Manual Temperature Control (EMTC) system, voltage is sent to the IC from the HVAC module - EMTC, then a message is sent from the IC through the HS-CAN bus to the PCM.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- PCM
- HVAC module - DATC
- HVAC module - EMTC
PINPOINT TEST N: THE AIR CONDITIONING (A/C) IS ALWAYS ON - A/C MODE ALWAYS COMMANDED ON
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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.
- Select the OFF position on the HVAC module.
- Does the ACCS PCM PID read ON?
Yes
For DATC systems, GO to N2.
For EMTC systems, GO to N3.
No
GO to N6.
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N2 CHECK THE AIR CONDITIONING SWITCH STATUS (CC_AC) HVAC PID WITH THE A/C OFF
- Enter the following diagnostic mode on the scan tool: CC_AC HVAC PID.
- Select the OFF position on the HVAC module.
- Does the CC_AC HVAC PID read ON?
Yes
GO to N5.
No
GO to N6.
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N3 CHECK HVAC - EMTC A/C REQUEST OUTPUT
NOTICE: The following step uses a test light to simulate normal circuit loads. Use only the test light recommended in the Special Tools table at the beginning. To avoid connector terminal damage, use the Flex Probe Kit for the test light probe connection to the vehicle. Do not use the test light probe directly on any connector.
- Ignition OFF.
- Disconnect: IC C220.
- Ignition ON.
- Select the OFF position on the HVAC module - EMTC.
- Connect a 12-volt test light between IC C220-23, circuit CH434 (GY/YE), harness side and IC C220-19, circuit SBP26 (YE/RD), harness side.
- Does the test light illuminate?
Yes
GO to N6.
No
GO to N4.
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N4 CHECK CIRCUIT CH434 (GY/YE) FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: HVAC Module - EMTC C2357A.
- Measure the resistance between IC C220-23, circuit CH434 (GY/YE), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to N5.
No
REPAIR circuit CH434 (GY/YE) for a short to ground. TEST the system for normal operation.
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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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