AC Compressor Clutch Not Engaging : Causes & Quick Fixes

AC Off Due To High Engine Temperature

Many times, you face problems like the AC compressor clutch not angaging. Often, this problem is caused by a problem or component failure in the air conditioning system. This clutch is an important part of the air conditioning system. But sometimes you also see that, for some reason, the clutch of the AC compressor does not angage with the rotation pulley and the AC compressor does not start.

In this post we will learn in detail about all the reasons for AC compressor clutch not engaging. So that you can identify the cause of this problem and find its appropriate solution.

What Is AC Compressor Clutch?

In a vehicle’s air conditioning system, the clutch is a part of the AC compressor. It is designed to connect and remove the AC compressor with a pulley rotating continuously with the engine, by which the AC compressor is switched on or off.

When we press the AC button from inside the cabin of the vehicle, the DC power supply reaches the magnet coil of the AC compressor, thereby creating a magnet. Through this process, the AC clutch is pulled and annexed to the rotation pulley, and the compressor starts rotating continuously with the engine.

Why is Your AC compressor Clutch Not Engaging – Causes

Causes of the AC compressor clutch not engaging may include damaged wiring or blown fuse, a bad AC control panel, a faulty power relay, a faulty clutch coil, a leaking evaporator coil, or a bad engine temperature switch.

Let us know all its reasons in detail, one by one.

1. Damaged Wiring or Blown Fuse


The air conditioning system in cars is a mechanical part. But this air conditioner system also has some electrical functions. like a magnet coil. The biggest reason for a car’s AC clutch not engaging is damaged wiring or a blown power supply fuse. Because there is no power supply to the magnet coil due to damaged wiring or a blown fuse and the magnet coil stops making magnets. Due to this, the AC clutch does not engage with the rotational pulley of the compressor.

2. Bad Control Panel or Power Relay


Sometimes the AC clutch does not engage even when the power on/off button to start the AC is faulty. In many cases, the AC clutch is not engaging due to a faulty power relay in the fuse box.

Because the power supply does not reach the AC magnet coil due to the failure of this button or the failure of the AC relay, the magnet is not formed in the magnet coil. Due to this, the magnet coil is unable to engage the rotational pulley of the AC clutch.

3. Faulty AC Clutch or Worn Rotation Pulley

ac clutch not engaging

Sometimes the reason for the non-engagement of the AC clutch is a bad AC clutch. Because the AC clutch’s tensioner rod becomes hard when the clutch is old or has not been used for a long time, it cannot be attracted by the magnet coil or the surfaces of both the AC clutch and the rotation pulley could be worn excessively. Because of the friction, the surface of the AC clutch and rotation pulley becomes smooth or loose. When this happens, the AC clutch is not engaging properly.

4. Brunt AC Clutch Magnet Coil

brunt ac clutch coil

A magnet coil is an important component in the AC compressor of cars or other vehicles, due to which the rotation pulley engages with the AC clutch. But sometimes the magnet coil gets burned due to overheat and gets burnt. Due to this, the AC clutch does not engage even when the air conditioner system is on.

5. Leaking Evaporator Coil (Cooling Coil)

leak evaporator

The evaporator coil is often fitted inside the dashboard of the vehicle’s cabin. which is an important part of the entire air conditioning system of the vehicle. Inside this coil, the refrigerant cools down and passes through fine channels and the blower fan installed in front of this evaporator coil pulls the air from the middle of this coil and throws it out through the vents.

But sometimes it leaks for some reason. Due to this, the clutch of a compressor is not engaged. because the amount of refrigerant gets reduced due to leakage. or may disappear completely.

6. Damage Parts Of The Air Conditioner System

The ac compressor clutch not engaging can also be due to wear and tear of air conditioner system parts. such as an expansion valve blocked or broken, an AC condenser clogged or leaking, a suction pipe line broken or leaking, an AC receiver dryer leaking or broken, etc. Because of all these reasons, the refrigerant may run out or its flow may stop. Because of this, the AC clutch does not engage.

7. Bad EngineTemperature Switch

ECM is used to control all the functions of cars or modern vehicles. The ECM manages all the functions of the vehicle properly. The engine coolant temperature switch also plays an important role in the air conditioner system. If this engine coolant temperature switch goes bad, or the engine starts to overheat.

This switch then sends an engine overheat signal to the vehicle’s ECM. Due to this, the ECM shuts off the automatic power supply to the AC compressor. Due to this, the clutch of the AC compressor is not engaged.

How To Fix AC Compressor Clutch Not Engaging?

There can be many reasons for the compressor clutch not engaging in a car’s air conditioning system. You have to check all these reasons one by one and fix this problem. such as:

  • First of all, check the wiring, fuse and power relay of the air conditioner system. If the wiring of the air conditioner system is damaged, repair it; if the fuse and power relay are damaged, replace them with a new one.
  • Check for refrigerant leakage. Also, after repairing the leakage of refrigerant, fill the system with a suitable refrigerant in a sufficient quantity.
  • Check all parts like the AC condenser, expansion valve, suction pipe line, receiver dryer, and cooling coil. If any of these parts are defective, repair or replace them.
  • Inspect the AC clutch magnet coil. if it is bad or burnt. Then you replace this clutch magnet coil as well.
  • Check the surface of the AC clutch and pulley. If there is a problem with friction between the clutch and the pulley, then these parts of the compressor will also have to be replaced.
  • If the serpentine belt is loose or broken, replace it with a new one.
  • The bearing of the AC compressor also needs to be checked. because broken bearings can completely jam the AC compressor.
  • Through all these processes, you can fix the AC clutch that is not engaging.

How To Diagnose AC Compressor Clutch Not Engaging?

To diagnose this, the following process has to be repeated, which is as follows:

  • First, disconnect the wire connector from the AC compressor.
  • After that, turn on the AC power button by turning the engine on.
  • Next, check the power supply at the wire coming to the AC compressor on the ECM side with a voltmeter or LED bulb.
  • If the power supply is interrupted, you will need to check the wiring, fuse, and power control relay. Also check the AC power on/off button.
  • Next, check the ground connection at the AC compressor.
  • After this, try supplying it directly from the battery in the connector of the AC clutch magnet coil. If the magnet coil is correct, then you will hear a clicking or knocking sound as soon as the direct power supply is applied. and will engage the AC clutch with the pulley.
  • This means that your vehicle’s AC clutch and magnets are correct.
  • The problem is with the power supply coming from the ECM.
  • In this way, you can diagnose an AC clutch that is not engaging.

How To Manually Engage AC Compressor Clutch?

To manually engage this compressor, you will need a jumper cable or a 2 to 3 meter piece of wire. Connect one end of this wire to the positive terminal of the battery and connect the other end of this wire to the single wire of the AC compressor.

You will not need to connect the negative wire because the negative wire of the AC compressor is already permanently connected to the ground connection. In this way, you can manually engage the AC compressor.


Q. How do I get my AC compressor clutch to engage?

To manually engage the clutch of the car’s AC compressor, you will need to disconnect the compressor’s wire connector. Now in the single positive wire of AC compressor, power supply will have to be given directly from the battery to the positive terminal through jumper cable.

Q. Can you turn the ac clutch by hand?

Yes, you can operate the clutch of a switched-off AC compressor by holding the clutch finger with your hand.

Q. Should I replace the AC compressor or just the clutch?

It depends on your budget and convenience. because replacing the AC compressor with a new one becomes a costly affair and the cost of just replacing the clutch is very low. So you have to choose whether you want to replace only the clutch of the compressor or the entire compressor. However, in cases of compressor clutch failure, it is advisable to replace the compressor itself. Because of this, you can avoid the possibility of inconvenience during the journey.

Q. Can you drive without AC compressor clutch?

Yes, if you don’t need to run the AC at that time. Then you can drive with the AC compressor off or with a bad clutch. because the pulley fitted in the compressor can rotate continuously without any problem. Only you can turn on the air compressor at that time.

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