AutoCodes – Chevrolet – P0645 2017 Chevrolet Silverado

P0645 2017 Chevrolet Silverado Code - Air Conditioning Compressor Clutch Relay Control Circuit

Quick Answer

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. Common causes include 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. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P0645 2017 Chevrolet Silverado indicates Air Conditioning Compressor Clutch Relay Control Circuit.
Common causes: Common causes include 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.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 532

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Jul 17, 2022

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P0645 2017 Chevrolet Silverado 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 P0645 2017 Chevrolet Silverado - Air Conditioning Compressor Clutch Relay Control Circuit - AutoCodes.com — P0645 2017 Chevrolet Silverado Code - Air Conditioning Compressor Clutch Relay Control Circuit

What does this mean?

What are the Possible Causes of the DTC P0645 2017 Chevrolet Silverado?

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)

How to Fix the DTC P0645 2017 Chevrolet Silverado?

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

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0645 2017 Chevrolet Silverado code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the P0645 2017 Chevrolet Silverado code?

Need more information on how to fix the P0645 2017 Chevrolet Silverado code? Get Access to Factory Service Manuals

Need Help with the Code?

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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.

Frequently Asked Questions about P0645 2017 Chevrolet Silverado Code

1. What does the OBDII code P0645 mean on a 2017 Chevrolet Silverado?

P0645 indicates a problem with the Air Conditioning (A/C) Compressor Clutch Relay Control Circuit, which may prevent the A/C system from functioning properly.

2. What are the common symptoms of code P0645 in a 2017 Chevy Silverado?

Symptoms include the A/C not blowing cold air, the A/C compressor not engaging, and possibly an illuminated check engine light.

3. What are the potential causes of the P0645 code?

Common causes include a faulty A/C compressor clutch relay, damaged wiring or connections in the control circuit, a malfunctioning A/C compressor clutch, or a problem with the Powertrain Control Module (PCM).

4. How do you diagnose the P0645 code?

Diagnosis involves checking the A/C compressor clutch relay, inspecting the wiring and connectors for damage, testing the A/C compressor clutch, and using a scan tool to monitor PCM commands.

5. Can a bad A/C compressor clutch relay cause the P0645 code?

Yes, a faulty or failing A/C compressor clutch relay is one of the most common causes of this code.

6. Can I still drive my 2017 Silverado with the P0645 code?

Yes, the vehicle is typically drivable, but the A/C system may not work, which can be uncomfortable in hot weather.

7. How can I fix the P0645 code on my Silverado?

Repairs may include replacing a faulty A/C compressor clutch relay, repairing or replacing damaged wiring or connectors, or replacing the A/C compressor clutch if it's defective.

8. How much does it cost to fix the P0645 code?

Repair costs depend on the issue, ranging from $50-$150 for a relay replacement to $500-$1,000 or more if the A/C compressor needs replacement.

9. Can a software issue in the PCM cause the P0645 code?

Yes, although less common, a software malfunction or internal failure in the PCM could cause this code and may require reprogramming or PCM replacement.

10. Do I need professional help to fix the P0645 code?

While some fixes like replacing the relay can be DIY, diagnosing and repairing wiring issues or PCM faults may require professional expertise and tools.