How To Manually Engage AC Compressor Clutch: The Easiest Methods

An automobile can have numerous serious problems and a dysfunctional AC compressor clutch is one of them. When this component does not work properly, the engine does not get the cold air flow – leading to some major complications. Knowing how to manually engage AC compressor clutch will help you skip a visit to the mechanic. Plus, you should also know how to examine the clutch to find out if it is faulty or not.

What Is An AC Compressor Clutch?

An air-conditioning unit in a car is made up of 5 main components: the compressor, condenser, expansion valve, evaporator, and receiver drier. The compressor is located in the engine compartment and is belt-driven by the engine. And an AC compressor clutch is a device that allows the compressor to engage and disengage from the engine.

When the clutch is engaged, the compressor will turn on and start compressing the refrigerator. And when the compressor turns off, it also means that the clutch is disengaged. In most cases, the AC compressor clutch is controlled by an electromagnetic coil. When current flows through the coil, it will create a magnetic field, it will pull the clutch plate toward the pulley. The AC compressor clutch is a small part with the same size as a silver dollar and in most cars, this part is positioned at the front of the compressor.

How To Examine The AC Compressor Clutch?

Using low-quality oil could be a reason for failing AC compressor clutch but it could happen even if you use synthetic oil and high-quality coolant. In a few cases, the clutch does not engage due to a clogged refrigerant circuit.

If you want to diagnose an AC compressor clutch for defects, apply these techniques:

Working method 1

Set all air conditioning controls to the MAX before kicking off the engine. Check the front side of the clutch to examine its condition. Also, find out whether the clutch and the pulley are spinning. If only the pulley is rotating, the compressor clutch is having an issue, which could be stemming from several sources – a blown fuse, bad clutch oil, low-pressure lockout, or an open wire in the oil.

how to manually engage AC compressor clutch
Put the AC on MAX before checking the compressor. (Photo:

Working method 2

Before starting the next step of diagnosis, you should know that a low-pressure switch can create problems with the compressor clutch’s relay in some car models. The system’s computer keeps the relay grounded but it can go on and off due to the bad switch. A careful inspection of the system and its components will help you to pinpoint the source of trouble.

In this step, you have to detach the connector cable from the clutch oil. Keep it safe away from all other components. Use a digital voltmeter to measure the ground and voltage of the battery at the detached connector cable. Go on to check the fuse if you cannot read the voltage readings. Move on to the clutch relay if the fuse turns out fine.

Working method 3

In a few car models, the power of the air conditioning system flows from the AC switch to the fuse before being transmitted to the clutch oil through the low-pressure evaporator temperature. You have to make sure that the compressor has enough oil to function properly.

When you are sure that there is a problem with the clutch, the next part is to engage it. The next section tells you how to manually engage AC compressor clutch at home.

Note that: Sometimes, your AC compressor clutch can get stuck, it’s usually caused by a lack of lubrication or a problem with an electromagnetic coil. When the clutch is stuck, it will make the compressor not disengage from the pulley and the consequence will be the AC compressor stays on all the time and the refrigerant accumulates.

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How To Manually Engage AC Compressor Clutch

Engaging the AC compressor clutch at home is not rocket science. There are a couple of ways you can fix the problem to bring back the air conditioning system in order.

Method 1: Add more coolant

What is the most common reason for an air conditioning compressor not to engage? Low level of refrigerant. When the coolant level in the system goes down, the low-pressure switch does not allow the compressor to rotate.

How to manually engage AC compressor clutch when the system is low on antifreeze? Easy. Just adding refrigerant will solve this problem. If your car is compatible with the R134a type of refrigerant, attaching a can to the system will override the low-pressure switch and restore the normal function of the compressor clutch.

Tips – When you are going to manually engage the compressor, make sure that the system has enough oil. Inadequate lubrication can damage the compressor.

how to manually engage AC compressor clutch
Adding a can of coolant is the easiest solution. (Photo:

Method 2: Jump-start the clutch

The process is a bit different for older cars that are not compatible with the R134a type. You have to jump-start it and the process won’t take more than a couple of minutes:

Examine the oil level in the compressor. Add oil if the level is below the normal point. Check the owner’s manual to check the correct instructions for checking up the compressor oil and level and filling it up.

Unplug the single-wire connector on the front side of the compressor. Take the fused jumper wire and connect its one end to that side of the wire connector that was connected to the compressor.

Attach the other end of the jumper wire to the positive terminal of the battery. It will supply the battery voltage to the compressor clutch, allowing it to engage manually. There is no need to switch on the air conditioning system for this method to work.

Tips – You should route the jumper wire to avoid it getting tangled or interfering with other moving components.

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Method 3: Replacing the clutch

It is an ominous sign when the clutch engages but the compressor does not spin. Changing the compressor clutch could be the only solution in this case. A bad AC compressor clutch needs immediate fixing. A delay can cause serious damage to the air conditioning system and the engine.