AutoCodes – Ford – P0645 2002 Ford F150

P0645 2002 Ford F150 Code - Wide Open Throttle A/C Cutout Primary Circuit Malfunction

Quick Answer

A/C clutch relay may also be referred to as A/C compressor clutch relay. Common causes include Faulty Air Conditioning Clutch Relay, Air Conditioning Clutch Relay harness is open or shorted, Air Conditioning Clutch Relay circuit poor electrical connection. 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: P0645 2002 Ford F150 indicates Wide Open Throttle A/C Cutout Primary Circuit Malfunction .
Common causes: Common causes include Faulty Air Conditioning Clutch Relay, Air Conditioning Clutch Relay harness is open or shorted, Air Conditioning Clutch Relay circuit poor electrical connection.
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.

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Code Popularity 2,243

How popular is this code, among other codes? Low

Repair Importance Level

Low (Monitor) (1 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on May 01, 2019

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0645 2002 Ford F150 Description

A/C clutch relay may also be referred to as A/C compressor clutch relay. A/C clutch relay circuit is monitored when ignition is on and battery voltage is greater than 10.4 volts.

OBDII Code P0645 2002 Ford F150 - Wide Open Throttle A/C Cutout Primary Circuit Malfunction - AutoCodes.com — P0645 2002 Ford F150 Code - Wide Open Throttle A/C Cutout Primary Circuit Malfunction

What does this mean?

What are the Possible Causes of the DTC P0645 2002 Ford F150?

Faulty Air Conditioning Clutch Relay
Air Conditioning Clutch Relay harness is open or shorted
Air Conditioning Clutch Relay circuit poor electrical connection
Damaged PCM

How to Fix the DTC P0645 2002 Ford F150?

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 does this mean?

Code Tech Notes

For applications that use a normally open relay to control the A/C clutch, the following description applies to the A/C clutch relay control circuit.
Monitors the wide open throttle A/C cutoff (WAC) circuit output from the PCM. The test fails if: When the PCM grounds the WAC circuit, excessive current draw is detected on the WAC circuit; or with the WAC circuit not grounded by the PCM, voltage is not detected on the WAC circuit (the PCM expects to detect VPWR voltage coming through the WAC relay coil to the WAC circuit).

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0645 2002 Ford F150 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.

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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 2002 Ford F150 Code

1. What are the common symptoms of OBDII code P0645 on a 2002 Ford F150?

The common symptoms include the A/C compressor not engaging, the Check Engine light being illuminated, and potential issues with the vehicle's air conditioning system.

2. What does the OBDII code P0645 indicate in a 2002 Ford F150?

OBDII code P0645 indicates a Wide Open Throttle A/C Cutout Primary Circuit Malfunction, meaning there is a problem with the circuit that controls the A/C compressor during wide-open throttle conditions.

3. What are the possible causes of the P0645 code in a 2002 Ford F150?

Possible causes include a faulty A/C cutout relay, wiring issues in the A/C circuit, a defective PCM (powertrain control module), or a malfunctioning A/C compressor.

4. How can I diagnose the P0645 code on my 2002 Ford F150?

Diagnosing the P0645 code involves checking the A/C cutout relay, inspecting the wiring for any damage or loose connections, testing the PCM for proper operation, and ensuring the A/C compressor is functioning correctly.

5. Can I continue driving my 2002 Ford F150 with the P0645 code?

It is generally not recommended to drive with the P0645 code present, as it can affect the performance of the A/C system and potentially lead to further issues with the vehicle's operation.

6. How can I repair the P0645 code on my 2002 Ford F150?

Repairing the P0645 code may involve replacing the faulty A/C cutout relay, repairing any damaged wiring, resetting the PCM, or replacing the A/C compressor if necessary.

7. Is it possible to reset the P0645 code on a 2002 Ford F150 without fixing the underlying issue?

While you may be able to clear the code temporarily, it will likely reappear if the root cause of the issue is not addressed. It's essential to diagnose and repair the problem to prevent further issues.

8. Can extreme weather conditions contribute to triggering the P0645 code in a 2002 Ford F150?

Extreme weather conditions, such as extreme heat or cold, can potentially affect the performance of the A/C system and contribute to triggering the P0645 code. Proper maintenance and care can help minimize these effects.

9. Will the P0645 code affect the overall performance of my 2002 Ford F150?

The P0645 code primarily affects the A/C system's operation during wide-open throttle conditions, so its impact on the overall performance of the vehicle may be limited. However, it's essential to address the issue to ensure proper functioning of the A/C system.

10. How can I prevent the P0645 code from recurring in my 2002 Ford F150?

Regular maintenance of the A/C system, checking for any wiring issues, and ensuring the proper operation of the A/C cutout relay can help prevent the P0645 code from recurring in your 2002 Ford F150.