What Should I Do If AC Compressor Clutch Is Not Engaging

If you get that the air conditioning (AC) compressor clutch is not engaging in your car, you might need to get some answers. In this article, you will learn what you can do during such a situation.

If the compressor clutch is not engaging, there are many possibilities. But you cannot use your air conditioning system when that happens. The compressor clutch is an integral element of your car’s AC system. So, rendering it inoperable is a great inconvenience for the passengers.

If your AC compressor clutch doesn’t engage, it means that your car will not be able to blow cool air into the vehicle. Even if you are using synthetic oil or coolant in your vehicle, the compressor clutch can get damaged due to some electrical problems too. Even a blockage in the refrigeration circuit can make the clutch not engaging.

Most cars currently use an electromagnetic AC clutch system to make the process of engaging and disengaging the AC compressor automatic. That makes operating the air conditioning system in your car more user-friendly and convenient. As you require the AC to work perfectly, we are going to give you the steps you need to take during such a situation.

But let's first learn some aspects of an AC compressor clutch.

What is an AC Compressor Clutch?

An air conditioning compressor clutch gets its power from the flywheel of your car’s engine. It is controlled using a clutch system where its shaft is engaged and disengaged to a rotating shaft of the flywheel using an electromagnetic switch.

The compressor and the clutch are two of the essential parts of the air conditioning system of your car. These parts, together with other car components, should be maintained properly to ensure they are functioning correctly at all times.

How Does an AC Compressor Clutch Work?

To use the air conditioning on your car when whenever you want, the clutch compressor is activated. To run this clutch compressor, the engine is connected directly to the pump rotor of the compressor using a belt. Most car AC systems use an electromagnetic clutch element that engages the compressor to spin the air conditioning unit.

The compressor clutch consists of a friction plate positioned adjacent to an electromagnetic coil. When the compressor clutch is engaged, a current moves through the electromagnetic coil. That creates a strong electromagnetic force that pulls the coil in the direction of the friction plate and engages the pump rotor, which consequently runs the compressor.

How to Determine Whether the Compressor Clutch Is Working

If the clutch doesn’t engage with the compressor, the pump will not work. When that happens, there will be no coolant or refrigerant that will go around the air conditioning system to cool your car.

To check if the clutch is working properly or not, try using these methods:

  • Turn on the air conditioning controls to maximum AC.
  • Start the engine
  • Look closer at the front of your clutch
  • At this moment, the clutch and the pulley should be spinning
  • If the pulley is the only rotating part, the clutch is not operating.

Important tips: If you are not an expert in car repairs. I'd suggest you work together with a Car Diagnostic Tool, according to Smart motorist, Most scan tools will plug directly into your dash and even send you notifications when there is an issue with your vehicle.   This is not just for AC Compressor issues but almost all issues related to the engine.

What Can Make The Clutch Not Engage?

Below are some of the possible reasons why the clutch doesn’t engage with the compressor:

  • Inadequate oil in the compressor
  • Excess refrigerant
  • Insufficient refrigerant
  • Defaulting on lockout on the clutch sensor: Most modern cars have air conditioning compressor clutches that are turned on and off by the high-pressure and low-pressure switches and the level of compressor oil through the fuse. These three aspects can disable the clutch to engage if the sensor notices that the compressor has insufficient oil, has excess refrigerant, or is low on refrigerant.
  • Burnt fuse: To know whether the fuse is burnt, switch off the car engine and disconnect the fuse from the system. Check the fuse utilizing a multimeter or any other instrument that can detect its situation. If the fuse is not busted, return it to its original position.

What Should I Do If AC Compressor Clutch Is Not Engaging?

Here are some of the possible steps that you can take to correct the issue:

  1. Checking the oil levels in the compressor

The compressor oil level can be easily seen from its display glass. Enough oil is shown by a red line in the display glass. If the level considerably drops below the red line, you need to add oil. Ensure that you add a type of oil that is compatible with your specific compressor. Use compressor oils that are approved by your air conditioning system’s manufacturer. You can check the specifications in the user manual.

  1. Discharging overcharged refrigerant

If the compressor gets overcharged with a refrigerant, the system will read abnormally high pressure. You can check the manual of your air conditioning system to determine the right operating pressure on the high-pressure side.

If you are certain that the compressor is overcharged, drain the refrigerant using a discharge valve positioned near the gauge. Bleed until you get the appropriate level of pressure.

  1. Compressor too low on refrigerant

You should check if the level of coolant in the compressor is too low by checking whether the pressure gauge of the high-pressure side of the compressor registers a pressure that is lower than what is needed. You can check your car's air conditioning manual for the right level of pressure.

There are repair kits for charging your refrigerant available, and they come with instructions on how to recharge the coolant.


It is not hard to diagnose the malfunctioning of your AC compressor clutch. You can determine if there is something wrong with the air conditioning system if something is not working. If the DIY tips don’t deliver the results, you can take the car to your mechanic and let him do a complete checkup of the AC system.

The AC compressor clutch is designed not to engage when there is something wrong in the system. Therefore, the next time the clutch is not engaging, check these elements occasionally to avoid issues:

  • Compressor oil,
  • Coolant or refrigerant
  • Fuse

We hope that the article was helpful!

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