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P0645 is a diagnostic trouble code (DTC) for "A/C Clutch Relay Control Circuit". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic for $79.99. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.
If your PCM has stored a P0645 code, it means that a problem has been identified in the A/C clutch relay control circuit.
This code can be identified by the PCM, or by one of the following supporting modules:
If there is a fault in the A/C clutch relay control circuit, the system will record a trouble code, and your Check Engine Light will come on. This may not happen right away – with some vehicles, it can take as many as eight failures before the Check Engine Light is activated.
Usually, the cause is a defective A/C compressor driver or A/C compressor control relay. Other causes could be:
You may not notice any symptoms other than an illuminated Check Engine Light. You could also see an illuminated or flashing A/C Malfunction light. If the Check Engine Light has not come on, the system may have stored the code as pending. If you are driving in hot weather, though, you may find that your air conditioning works poorly, if at all.
The mechanic will use a code reader and ohmmeter in order to diagnose the code. Then, he or she will:
Frequently, a mechanic will simply replace an entire wiring harness rather than attempt to repair various components. This is because the diagnostics can be so complicated and time-consuming. A full replacement is often more cost-effective for the customer.
The most common mistake when diagnosing the P0645 code is to misdiagnose the symptoms and codes. This is because of the complexity involved. Often, the wrong components are repaired or replaced.
That really depends on how much you value your air conditioning. Some drivers never use it, being content to just drive around with their windows down. For others, air is an absolute must. Suffice it to say, though, that this is not a problem that is ever going to endanger you or your passengers, so you can take your time having it dealt with, if you choose to deal with it at all.
Corroded or otherwise damaged wires can be replaced, or if the source of the problem is not easily identifiable, the entire wiring harness can be replaced. Sometimes this is the more affordable option.
Having to do without air conditioning in your car is inconvenient. If you prefer to drive in comfort, and you’re A/C isn’t working properly, contact us at YourMechanic. You can reach us at 1-800-701-6230, or request an appointment using our online form. We will send a qualified mobile mechanic to the location of your choosing to fix you’re A/C. We’ll also be happy to provide you with a free quote.