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P0646 2016 GMC Sierra Code - Air Conditioning Compressor Clutch Relay Control Circuit Low Voltage

Quick Answer

The P0646 diagnostic trouble code (DTC) for a 2016 GMC Sierra relates to the Air Conditioning Compressor Clutch Relay Control Circuit registering low voltage. Common causes include Faulty air conditioning compressor clutch relay, Wiring issues such as frayed or damaged wires, Poor electrical connection at the relay or compressor. Severity is Low - monitor the vehicle and repair when practical. The vehicle can usually be driven if no severe symptoms are present, but symptoms should be checked before extended driving.

What it means
P0646 2016 GMC Sierra indicates Air Conditioning Compressor Clutch Relay Control Circuit Low Voltage.
Common causes
Common causes include Faulty air conditioning compressor clutch relay, Wiring issues such as frayed or damaged wires, Poor electrical connection at the relay or compressor.
Severity
Low - monitor the vehicle and repair when practical.
Can I drive?
The vehicle can usually be driven if no severe symptoms are present, but symptoms should be checked before extended driving.
What is this?
Table of contents Created and updated by William Orellana on Sep 15, 2024
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Code P0646 2016 GMC Sierra Description

The P0646 diagnostic trouble code (DTC) for a 2016 GMC Sierra relates to the Air Conditioning Compressor Clutch Relay Control Circuit registering low voltage. This code indicates that there is an issue with the electrical circuit responsible for controlling the air conditioning compressor clutch relay, which plays a crucial role in the operation of the vehicle's air conditioning system. The air conditioning compressor clutch relay is responsible for engaging and disengaging the compressor, which is essential for the proper functioning of the air conditioning system.

OBDII Code P0646 2016 GMC Sierra - Air Conditioning Compressor Clutch Relay Control Circuit Low Voltage
P0646 2016 GMC Sierra Code - Air Conditioning Compressor Clutch Relay Control Circuit Low Voltage

Common Causes of P0646 2016 GMC Sierra

  1. Faulty air conditioning compressor clutch relay.
  2. Wiring issues such as frayed or damaged wires.
  3. Poor electrical connection at the relay or compressor.
  4. Defective compressor clutch.
  5. Issues with the vehicle's electrical system.

Symptoms of P0646 2016 GMC Sierra

  1. Lack of cold air coming from the air conditioning system.
  2. Air conditioning system not engaging at all.
  3. Inconsistent cooling performance.
  4. Illumination of the check engine light on the dashboard.
  5. Unusual noises coming from the air conditioning system.

How to Fix P0646 2016 GMC Sierra

  1. Begin by conducting a thorough inspection of the wiring and connectors related to the air conditioning compressor clutch relay control circuit.
  2. Test the air conditioning compressor clutch relay to determine if it is functioning correctly. Replace if necessary.
  3. Check the compressor clutch for any signs of damage or wear. Replace if needed.
  4. Verify the voltage levels in the control circuit and address any low voltage readings by repairing or replacing faulty components.
  5. Clear the DTC and test the air conditioning system to ensure proper functionality.

Cost to Fix P0646 2016 GMC Sierra

The typical repair costs for addressing a P0646 code on a 2016 GMC Sierra can range from $150 to $400, depending on the specific cause of the issue and the cost of parts and labor. It is important to note that diagnosis time and labor rates can vary based on factors such as location, vehicle make and model, and engine type. Auto repair shops commonly charge between $80 and $150 per hour for labor, with rates potentially higher in metropolitan areas or at dealerships, and lower at independent shops. For a more precise estimate, it is recommended to inquire with local auto repair shops.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

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