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If the AC compressor on your classic car has stopped working and you would rather not replace it, installing an AC compressor bypass pulley is a viable option for safely and efficiently removing your factory AC compressor.

Install Level of Difficulty


What is an AC Compressor Bypass Pulley?

To bypass or remove the factory AC system, the bypass pulley is installed in place of the factory compressor. You may not even need to change your serpentine belt, but Pep Boys recommends replacing it if you don’t know the last time it was changed. Alternately, you may need to purchase an AC compressor bypass belt sized to fit your engine.

How do AC Compressor Bypass Pulley Work?

Why not just leave the broken factory compressor in its place and ignore it? Although your engine will run fine, it won't produce as much power with the factory compressor as it will after you bypass the AC compressor with an aftermarket pulley. Simply put, the bypass pulley spins with far less rolling resistance than your factory AC compressor. This increases your engine's power output and, at the same time, allows you to dress up your engine bay.

How are AC Compressor Bypass Pulley Made?

AC bypass pulleys are mass-produced using heavy factory machinery, just like most of the other steel and aluminum parts assemblies found on your vehicle.

Why do AC Compressor Bypass Pulley Fail?

  • AC bypass pulleys fail if the bearings inside become worn and corroded.
  • AC bypass pulleys are often installed as a response to a failing AC system that could be difficult or expensive to repair.
  • Improper belt installation, or installing the wrong belt, could result in premature bearing and pulley failure.

What are the Symptoms of AC Compressor Bypass Pulley Failure?

  • Screeching, squealing, or grinding noises may be heard under the hood of the vehicle while the engine is running.
  • If the pulley seizes, your serpentine belt may break soon after.

What are the Consequences of AC Compressor Bypass Pulley Failure?

  • If your serpentine belt breaks due to a seized pulley, all your engine’s accessories will lose power, including the water pump and alternator.
  • Running a non-functional AC compressor reduces power output and gas mileage.
  • Improper removal of factory AC components could leak refrigerant into the atmosphere. Schedule an appointment at your local Pep Boys if you lack the proper tools to purge your factory AC system.

AC compressors are expensive and difficult to replace on some vehicles. On some older vehicles, factory AC compressors are unavailable. In these instances, you may want to consider installing a bypass pulley kit. Installing an AC bypass pulley is considered a high-performance modification.

If you have questions or concerns about AC compressor bypass pulleys or any of your vehicle's components, come into your local Pep Boys where we can answer any question, help you find any part, or perform any vehicle service you might need.