AC Clutch Engages Intermittently? Let’s Find Out The Reason & Solution

The most typical cause of the AC clutch engaging intermittently and your car’s compressor turning on and off quickly is that the AC system is short on freon or has low pressure as a result of leaks or defects in the components of the AC system. Short cycling of the AC compressor is another effect of the clutch occasionally disengaging due to poor electrical connections of the AC compressor coil.

So you set out on a lengthy drive or road trip and discovered after 30 minutes that your air conditioning had abruptly stopped working or had begun blowing heated air. Shortly after, the cold air returns, and the cycle continues as long as you are driving. What is wrong with your car? Why AC clutch engages intermittently and how to fix this problem.

Why AC Clutch Engages Intermittently 

Frozen AC system parts in your car are a common source of intermittent cooling. Usually, an evaporator that has iced over is to blame. You would need to wait until the ice melted in order for an evaporator covered in ice to chill the air, which is why the cold air ultimately returns. There might be a number of problems causing the ice, such as a clogged evaporator drain, an overcharged system, or a filthy cabin air filter. Look for water pools under your car; these can indicate a freezing issue.

Here are some typical reasons explaining why AC clutch engages intermittently;

1.Slipping Clutch of A/C Compressor

A sliding clutch plate is the most frequent cause of intermittent engagement and disengagement of the AC clutch. Serious wear or a widening gap between the friction plate and compressor pulley are indicators of a sliding clutch.

Pulleys and clutch plates are made to fit together tightly. The clutch will slip and fail to engage if they deteriorate and become loose. If the air gap between the pulley and clutch plate develops past a certain point, clutch plate damage may also result. This is typically caused by a compressor that is overheated or by broken bearings.

The strength of the AC clutch coil influences the air gap between the clutch’s friction plate and pulley, which is controlled by the automaker.

The magnetic field won’t be strong enough to draw and securely hold the friction plate of the clutch against the pulley if the air gap between the plate and the pulley is enlarged. As a consequence, the AC clutch will occasionally disengage and the AC vents won’t blow cold air.

2. Bad Electric Connection In Compressor Clutch Coil 

The AC clutch would also disengage sporadically if there was less than 12 volts at the AC compressor coil. As a result, the clutch would occasionally slide, which would result in the compressor clutch occasionally disengaging.

The electrical cable at the compressor coil may be broken or disconnected, which would create this issue. It could occur as a result of a short circuit. Or, a blown fuse can be to blame. The fuses on the compressor coil of the air conditioner should be examined, and if required, replaced.

3. Low or High Refrigerant Pressure

If the pressure of the freon entering the evaporator is less than 30 psi or greater than 250 psi, the AC compressor clutch also engages and disengages intermittently. Each refrigerant has a distinct pressure limit.

Only when there is enough pressure in the system (30 psi) to close the low-pressure switch and not enough high pressure to open the high-pressure switch and interrupt current flow will the AC clutch engage.

When a result, the AC clutch will engage, disengage, and re engage as the pressure between the high and low pressure sides equalizes if the refrigerant pressure in the system is low.

How To Fix AC Clutch Engages Intermittently

When you’re driving, does the air in your car occasionally change from frigid to lukewarm and humid? There’s a potential that your car’s AC clutch will only sometimes activate. In that case, the air conditioner blasts chilly air for around five to twenty minutes before turning off once more. At high RPMs, or above 4000, some users are also able to obtain cold air from the AC once again. All of these symptoms are related to the AC’s brief cycling. Let’s get started by talking about all of the potential reasons why the AC clutch engages and disengages.

1.How To Fix Slipping Clutch of A/C Compressor

You can use a feeler gauge to measure the space between the clutch’s friction plate and compressor pulley.

Make careful to check the gap before starting the engine. The pulley and friction plate nominal air gap settings can range from 0.3 mm to 0.8 mm. You must replace the clutch assembly if the air gap is more than 1.0mm. Upon removing a clutch plate, a shim will be seen (a small metal disc). The shim determines the appropriate distance between the friction plate and pulley. An adjustable shim with various thicknesses may be used to change the air gap.

Additionally, look to see whether the color of the compressor clutch’s friction plate has faded or if it has burn marks. If so, you must swap out the clutch assembly.

2. How To Fix Bad Electric Connection In Compressor Clutch Coil 

Set a digital multimeter to the ohms scale and touch one lead to a clutch coil terminal and the other to a ground point on the compressor to check for a short to the ground of the compressor coil circuit. There won’t be any conductivity if there is a short circuit. The test should be carried out similarly for the coil’s other termination.

After that, measure the resistance between the compressor clutch coil’s terminals. The coil is defective if the resistance is less than 3 ohms or greater than 5 ohms.

Check the clutch relay next. If it is broken, the coil won’t get a proper voltage. Electrical contacts in the clutch relay eventually get pitted, which stops current flow. Therefore, unhook the compressor’s connector and check with a voltmeter to verify if it is receiving 12V. If not, the clutch relay has malfunctioned.

3. How To Fix Low or High Refrigerant Pressure

The AC system’s lack of freon may be indicated by the low pressure on the low-pressure gauge, which is located between the evaporator and compressor. Make sure there are no leaks in the system first, though, before continuing and injecting extra refrigerant within. You should inspect the AC compressor’s o-rings at its input and exhaust ports for leaks.

When the A/C system leaks again, you may trace all the hoses and connections by recharging it with a refrigerant that contains dye.

Similar to the low-pressure gauge, which is between the compressor and evaporator, excessive pressure there might mean that the system is overloaded with refrigerant. However, a blockage in the expansion valve or orifice tube may be the cause of the excessive pressure in the A/C system.

High pressure might also result from the condenser being clogged with dirt. The high-pressure side reading would be high and the low-pressure side reading would gradually decrease if there was an obstruction or limitation in the condenser’s airflow. Additionally, look for twisted condenser fins.

Additionally, make sure the desiccant in the accumulator or dryer/receiver is working properly. The pressure on the low and high pressure lines of the AC system will change if they are unable to contain any more moisture.

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