AutoCodes – GMC – P0645 2014 GMC Sierra

P0645 2014 GMC Sierra 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 2014 GMC Sierra 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 214

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 2014 GMC Sierra 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 2014 GMC Sierra - Air Conditioning Compressor Clutch Relay Control Circuit - AutoCodes.com — P0645 2014 GMC Sierra Code - Air Conditioning Compressor Clutch Relay Control Circuit

What does this mean?

What are the Possible Causes of the DTC P0645 2014 GMC Sierra?

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 2014 GMC Sierra?

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 2014 GMC Sierra 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 2014 GMC Sierra code?

Need more information on how to fix the P0645 2014 GMC Sierra code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P0645 2014 GMC Sierra code diagnosed by a professional: Find a repair shop in your area

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 2014 GMC Sierra Code

1. What are the common symptoms of OBDII code P0645 in a 2014 GMC Sierra related to the air conditioning compressor clutch relay control circuit?

The common symptoms include issues with the air conditioning system such as failure to engage the compressor clutch, intermittent cooling, or complete lack of cooling.

2. What causes the OBDII code P0645 to trigger in a 2014 GMC Sierra's air conditioning compressor clutch relay control circuit?

This code is typically triggered by a malfunction in the air conditioning compressor clutch relay control circuit, which can be caused by a faulty relay, damaged wiring, or a problem with the compressor itself.

3. How serious is the OBDII code P0645 in a 2014 GMC Sierra's air conditioning system?

While this code may not affect the drivability of the vehicle, it can lead to discomfort during hot weather due to the lack of proper cooling. It is recommended to address this issue to ensure the proper functioning of the air conditioning system.

4. Can I still drive my 2014 GMC Sierra with the OBDII code P0645 related to the air conditioning compressor clutch relay control circuit?

It is generally safe to drive the vehicle with this code, but it is advisable to get it diagnosed and repaired as soon as possible to avoid any potential issues with the air conditioning system.

5. How can I diagnose the OBDII code P0645 in my 2014 GMC Sierra's air conditioning system?

Diagnosing this code typically involves checking the air conditioning compressor clutch relay, inspecting the wiring for any damage, and ensuring that the compressor is functioning correctly. A professional diagnostic tool may be needed for a thorough diagnosis.

6. What are some repair tips for fixing the OBDII code P0645 in a 2014 GMC Sierra's air conditioning system?

Repair tips may include replacing the faulty air conditioning compressor clutch relay, repairing any damaged wiring, or addressing any issues with the compressor itself. It is recommended to consult a professional mechanic for accurate diagnosis and repair.

7. Can a DIY enthusiast fix the OBDII code P0645 related to the air conditioning compressor clutch relay control circuit in a 2014 GMC Sierra?

While some DIY enthusiasts may be able to address this issue, it is recommended to have a professional mechanic diagnose and repair the problem to ensure it is fixed correctly and prevent any further damage to the air conditioning system.

8. How much does it typically cost to repair the OBDII code P0645 in a 2014 GMC Sierra's air conditioning system?

The cost of repairing this issue can vary depending on the exact cause of the problem, the labor rates in your area, and the cost of any replacement parts needed. It is best to get a quote from a trusted mechanic.

9. Are there any preventative measures to avoid the OBDII code P0645 in a 2014 GMC Sierra's air conditioning system in the future?

Regular maintenance of the air conditioning system, including checking the relay and wiring for any signs of wear or damage, can help prevent this code from occurring. Additionally, addressing any issues with the compressor promptly can also help avoid this problem.

10. How long does it typically take to repair the OBDII code P0645 related to the air conditioning compressor clutch relay control circuit in a 2014 GMC Sierra?

The repair time can vary depending on the exact cause of the issue and the availability of parts. In general, it may take a few hours to a day for a professional mechanic to diagnose and repair the problem.