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P0646 Code - Air Conditioning Compressor Clutch Relay Control Circuit Low Voltage

- Code Popularity: 22,976 Views
- Repair Importance Level: 1/3
- Repair Difficulty Level: 3/3
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What are the Possible Causes of the DTC P0646?

NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.
  • Faulty Air Conditioning (A/C) Compressor Clutch Relay
  • Air Conditioning Compressor Clutch Relay harness is open or shorted
  • Air Conditioning Compressor Clutch Relay circuit poor electrical connection
  • Faulty Air Conditioning Compressor Clutch
  • Faulty Engine Control Module (ECM)
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How to Fix the DTC P0646?

Review the 'Possible Causes' mentioned above and visually examine the corresponding wiring harness and connectors. Ensure to check for any damaged components and inspect the connector pins for signs of being broken, bent, pushed out, or corroded.

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What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0646 code, it typically requires 1.0 hour of labor. The specific diagnosis time and labor rates at auto repair shops can differ based on factors such as the location, make and model of the vehicle, and even the engine type. It is common for most auto repair shops to charge between $75 and $150 per hour.

What are Code Possible Symptoms?

  • Engine Light ON (or Service Engine Soon Warning Light)

Code P0646 Description

When the Air Conditioning (A/C) switch is pressed, the Heating, Ventilation, and Air Conditioning (HVAC) control module sends an A/C request message to the Engine Control Module (ECM) via serial data. The ECM then grounds the A/C compressor clutch relay coil control circuit, closing the relay contacts. The closed relay contacts provide voltage to the compressor clutch causing it to engage. The Diagnostic Trouble Code (DTC) will be set when the ECM detects a short to ground or an open at the A/C compressor clutch relay control circuit.

OBDII Code P0646 - Air Conditioning Compressor Clutch Relay Control Circuit Low Voltage - AutoCodes.com
P0646 Code - Air Conditioning Compressor Clutch Relay Control Circuit Low Voltage

Need More Information on the Code?

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Information for Specific Makes

  • P0646 BMW Air Conditioning Clutch Relay Circuit Low
  • P0646 Buick Air Conditioning Compressor Clutch Relay Control Circuit Low Voltage  📷
  • P0646 Cadillac Air Conditioning Compressor Clutch Relay Control Circuit Low Voltage  📷
  • P0646 Chevrolet Air Conditioning Compressor Clutch Relay Control Circuit Low Voltage  📷
  • P0646 Chrysler Low Voltage Detected At The AC Clutch Relay
  • P0646 Dodge Low Voltage Detected At The AC Clutch Relay
  • P0646 GMC Air Conditioning Compressor Clutch Relay Control Circuit Low Voltage  📷
  • P0646 Hyundai Air Conditioning Clutch Relay Circuit Low
  • P0646 Jeep Low Voltage Detected At The AC Clutch Relay
  • P0646 KIA Air Conditioning Clutch Relay Circuit Low
  • P0646 Mazda Air Conditioning Clutch Relay Circuit Low
  • P0646 MINI Air Conditioning Clutch Relay Circuit Low
  • P0646 Suzuki Air Conditioning Clutch Relay Circuit Low

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