AutoCodes – Ford – P0645 2000 Ford F150

P0645 2000 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 2000 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 2,500

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 2000 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 2000 Ford F150 - Wide Open Throttle A/C Cutout Primary Circuit Malfunction - AutoCodes.com — P0645 2000 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 2000 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 2000 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 2000 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 2000 Ford F150 Code

What does the OBDII code P0645 mean on a 2000 Ford F150?

Code P0645 indicates a malfunction in the Wide Open Throttle A/C Cutout Primary Circuit, which controls the air conditioner operation under high engine load conditions.

What are the common symptoms of code P0645 on a 2000 Ford F150?

Symptoms may include the air conditioning not functioning properly, the A/C compressor failing to engage, or intermittent A/C operation.

What causes code P0645 in a 2000 Ford F150?

Common causes include a faulty A/C cutout relay, damaged wiring or connectors in the circuit, or a malfunctioning PCM (powertrain control module).

How can I diagnose code P0645 on a 2000 Ford F150?

Begin by inspecting the wiring and connectors for damage, test the A/C cutout relay, and check for proper voltage and ground signals. If no issues are found, the PCM may need further testing.

Can I drive my 2000 Ford F150 with code P0645?

Yes, you can drive the vehicle with code P0645, but the air conditioning may not function properly, and it may affect comfort during hot weather.

How do I fix code P0645 on a 2000 Ford F150?

Repairs may include replacing the A/C cutout relay, repairing damaged wiring or connectors, or reprogramming or replacing the PCM if necessary.

What tools are needed to diagnose and repair code P0645 on a 2000 Ford F150?

You may need a multimeter, wiring diagram, relay testing tool, and an OBDII scanner for proper diagnosis and repair.

Is code P0645 a common issue in a 2000 Ford F150?

It is not one of the most common issues but may occur due to aging components or electrical faults in the A/C system.

How much does it cost to fix code P0645 on a 2000 Ford F150?

Repair costs can vary depending on the required fixes, ranging from $50 to $300 for parts and labor, depending on whether you need a new relay, wiring repair, or PCM replacement.

Can code P0645 trigger other problems in a 2000 Ford F150?

While it primarily affects the A/C system, prolonged issues with the circuit can lead to electrical strain on related components.