What Should You Do When AC Compressor Clutch Not Engaging?

When the AC compressor clutch in your car suddenly stops working and does not engage, it could be a sign of serious problem as cool air flow would not be blown into the engine. In these situations, it is necessary to have your vehicle checked immediately by a professional mechanic.

Even when you are using the synthetic oil or the coolant in the industry, an AC compressor clutch could be loosened because of some electrical error fault as well. In some situations, a blocked refrigerant circuit would also make the AC clutch not to engage. To help you to solve this problem, we are going to give some simple steps in this article.

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How to Examine the AC Compressor Clutch​?

If your repeated tests have already gone wrong, and you have still not been able to manually engage the AC compressor clutch, then it is necessary to jump start it. To do this, you need to directly connect the wire of the clutch to a battery. It would be lucky if the AC could blow cool air and the compressor could engage. The main problem is possibly due to a pressure switch or faulty relay.

If the clutch engages but the compressor does not turn, it means that you probably need a new one. Nevertheless, if this does not help, it might be because you are using a bad AC compressor clutch. In those cases, you would require an immediate change service of the same.

Adjust all the controls of the AC to MAX and then start off the engine. Take a look at the front of the compressor clutch to see whether it as well as the pulley are spinning or not. If only the pulley rotates, there must be an issue in the system. The reasons would be due to bad clutch oil, poor ground, low-pressure lockout, a blown fuse or open wire in the oil.

Before you move to the next step, it is essential for you to understand the basic information of a couple components. In a couple car models, the relay of the compressor clutch goes on and off because of a low-pressure switch. However, this relay is grounded by the computer of a controlled system. You should carefully check all the parts of the system to find out the problem faster.

Start with removing the connector cable from clutch oil. You should take it away from other parts to have a more careful examination of ground and power. When the AC is still in MAX mode, take a digital voltmeter to measure the ground and the battery voltage at the removed connector. If you are not able to read the voltage results, examine the fuse. If everything is fine with the fuse, then you have to examine the clutch relay.

In some car models, the flow of power is from an AC switch to the fuse, then moves directly to the clutch oil via low-pressure evaporator temperature. Although this should not be a problem, you have to be sure that the AC compressor is filled with sufficient amount of oil to avoid any failure.

Low Amount of Coolant​

Being low on the refrigerant would be another cause for a non-engaging AC compressor clutch in your car. Low coolant pressure or content is really dangerous for your vehicle’s system. Although you can use DIY devices to recharge, it is also one of the common and major causes for engaging failure in a compressor clutch.

Do not try to apply DIY devices that operate by hot-wiring the low pressure’s switch and then make the compressor clutch to engage. Sometimes, it would work but is seen as a risky act due to oil shortage at the same time in the compressor. In fact, you would have caused several serious and permanent damage to the compressor by this time, which calls for a more extensive replacement or repair.


Therefore, use the octane booster or Freon coolant when you need to, but do not charge the system forcibly. If there is any leakage in the car’s system, you have to get it checked as soon as possible because it could make air and moisture to come in. As a result, moisture will combine with the coolant to create sludge and acid, which can damage the system. If this problem has already occurred, you would have to bleed it out.

It is quite simple to add more coolant even without a hot-wiring problem. Nevertheless, it is you who take the responsibility for the safety of your vehicle.

Our Recommendation​

We strongly suggest you to use the best car buffer, best OBD2 Scanner and best 10-inch subwoofer for your car when the AC compressor clutch does not engage.

However, you should not ignore the health of the vehicle. Whether it is the compressor, the coolant or the oil, you have to keep a watchful eye on all of them and try not to test too much on your own.

Call a professional mechanic immediately if you are not able to start or engage the AC compressor clutch.

Related Article: What Should You Do When Your Car AC Compressor Not Turning On?


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7 thoughts on “What Should You Do When AC Compressor Clutch Not Engaging?”

  1. i have 04 town car that doesn’t engage the clutch,i jumped the coil to the battery and is engaging and blowing nice cold air ,what happens if i use every time ,jumping the battery ,will damage some part or even danger of “explosion”the ac system?
    i wait for answer.thanks

    • Yes and not. Jumping the battery seems to be a normal task that most of us often do. But I have experienced some cases that caused a permanent damage in the AC system. Thus, you should consult your machenic for safety.

  2. I have a 2008 Mitsubishi outlander. I’ve inspected the fuses all are in good condition. Now when I have the a.c. on max cold and blowing max I just give the clutch a lil spin tap kinda deal with the rubber handle end of a hammer so I don’t loose any fingers and it engages and works fine, then I’ll let it run to see if it turns off and it doesn’t. But once I turn the air off to turn off the compressor and try turning the air back on the compressor does not engage what can the issue be??

  3. F250 New compressor not engaging, fuse and relays are good and so are the low n high pressure switch. I don’t know what to do next.

  4. Ac clutch not engaging, relay and fuses good. Get 13v to hot side of connector and read voltage through ground. Hot wired coil and no sound or click. Get 4k ohms across coil. Can i assume the clutch coil went bad.

  5. I have a 2002 F150…..AC was not working so I installed a new compressor. The compressor clutch would not engage so I installed a new low pressure switch and a high pressure switch and also installed a new relay. I put new refrigerant in it and made it 45lb. When i start the key the clutch will engage and spin for approx. 10 sec. and then stop? Do I need to add more refrigerant? it recommended 45 to 55 lb


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