What To Do When The Compressor

What To Do When The Compressor’s Magnetic Coupling Does Not Engage?

At the heart of your car’s A/C unit, lays the compressor. It is designed to pressurize the refrigerant and pump it through the air conditioning system. It typically derives its power directly from the engine flywheel. This process is similar to how the drive chain of the car and electromagnetic clutch control its operations. Compressors also comprise a mechanism that’s known as magnetic coupling. It transfers torque from one shaft to another via a magnetic field, i.e. without needing a physical mechanical connection.

How does the A/C Clutch and Compressor Work Together?

A/C compressors put Freon gas under pressure. With the presence of compression, the temperature of the gas rises above the ambient air. Next, the A/C compressor utilizes a pump mechanism to pressurize the gas. An engine then makes a rotor operate at high speeds, which doubles as a turbine that allows the Freon to enter the inlet valve. The compressor will continue to store the gas in a tank until the required pressure is reached. After that, it pumps the gas into the condenser.

As mentioned, car A/C units use a magnetic coupling mechanism to engage the compressor, and activate the A/C unit in the cabin. A/C clutches are known to have a friction plate that’s located adjacent to an electromagnetic coil. A powerful magnetic force is created when a current runs through this coil. The force is directed to the friction plate in the clutch. When these clutches are engaged, they drive the pump rotor in the compressor. As the friction plates need to return to their disengaged positions, springs are used to make that happen. When the current stops passing through the magnetic coil, the air conditioner is switched off.

Main A/C Clutch Mechanisms

A/C clutch mechanisms control the transfer of power by using five simple components. They are designed to engage the friction plates and provide excellent torque transfer efficiency, whilst preventing slippage. The key components include:

  • Electromagnetic coil: Attracts the armature by producing a magnetic field.
  • Clutch rotor: Constantly spins a friction plate. Powered by a motor.
  • Output hub: Responsible for transferring power to the compressor pump rotor
  • Armature: Attaches a friction plate to the rotor plate via magnetism
  • Armature springs: Stops the compressor by disengaging the clutch rotor and armature plate.

What to Do When the Magnetic Coupling Mechanism Fails to Engage

  • Compressor’s magnetic coupling affected by lack of proper clearance

The recommended magnetic coupling’s clearance should be configured between 0.4 to 0.6 mm.

  • Interrupted power supply or Loss of Refrigerant

In this case, you should check to see if there are any leaks in the cooling circuit. If the magnetic coupling does not engage at all, it is time to replace it. If it is the opposite, check the functioning of the electrical connections, A/C switch, thermostat, and pressure switch. In some cases, you may also need to remove the power cable to the magnetic coupling. Try connecting it directly to the car’s battery instead, with a 7.5A fuse.