Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Circuit/System Verification
Check for bulletins before proceeding.
- Ignition ON.
- Verify every applicable scan tool Switch parameter changes when pressing the appropriate switch on the A26 HVAC Controls.
- If any parameter does not change
Replace the A26 HVAC Controls.
- Go to next step: If all parameters change
- If any parameter does not change
- Verify the blower motor operates properly with the blower motor switch in each speed position.
- If the blower motor does not operate in each speed position
Refer to Blower Motor Malfunction (C41, C60) Blower Motor Malfunction (C67) .
- Go to next step: If the blower motor operates properly in each speed position
- If the blower motor does not operate in each speed position
- Verify the air inlet door works properly when commanded.
- If the air inlet door does not work properly
Refer to DTC B0223 (C60)
- Go to next step: If the air inlet door does work properly
- If the air inlet door does not work properly
- Install the appropriate ACR Air Conditioning Service Center, ignition ON.
- Verify the high side pressure reading on the Air Conditioning Service Center is within 10% of the scan tool ECM A/C High Side Pressure Sensor parameter.
- If the reading is not within 10%
Refer to DTC P0532 or P0533 .
- Go to next step: If the reading is within 10%
- If the reading is not within 10%
- Verify the ECM A/C High Side Pressure Sensor parameter is between 269-2929 kPa (39-425 PSI).
- If the reading is not between 269-2929 kPa (39-425 PSI)
- Go to next step: If the reading is between 269-2929 kPa (39-425 PSI)
- Verify the scan tool HVAC A/C Evaporator Temperature Sensor parameter listed is within 10% of ambient temperature.
- If not within 10% of ambient temperature
Refer to DTC B3933 .
- Go to next step: If within 10% of ambient temperature
- If not within 10% of ambient temperature
- Verify the A/C compressor clutch engages and disengages when commanding the ECM A/C Compressor Clutch Relay On and Off with a scan tool.
- If the A/C compressor does not engage
Refer to DTC P0645, P0646, or P0647
- Go to next step: If the A/C compressor does engage
- If the A/C compressor does not engage
- Engine ON, A/C system ON.
- Verify cool air flows from the ducts with the temperature control in the coldest position.
- If the air is not cool
- Verify the Q2 A/C Compressor Clutch is engaged.
- If the Q2 A/C Compressor Clutch is not engaged, refer to Air Conditioning Compressor Malfunction (C67) Air Conditioning Compressor Malfunction (C60) .
- If the Q2 A/C Compressor Clutch is engaged, refer to Air Conditioning (A/C) System Performance Test .
- Go to next step: If the air is cool
- Verify warm air flows from the ducts with the temperature control in the warmest position.
- If the air is not warm
Refer to Heating Performance Diagnostic .
- Go to next step: If the air is warm
- If the air is not warm
- All OK.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.