The electromagnetic clutch of an automobile air conditioner is a power transmission device between the automobile engine and the automobile air conditioner compressor. The automobile air conditioner compressor is driven by the automobile engine through the electromagnetic clutch.
The electromagnetic clutch of an automobile air conditioner is generally composed of three parts: the clutch pulley, the clutch coil, and the clutch hub. An electromagnetic clutch for an automobile air conditioner is a typical mechanical and electrical engineering product.
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Working Principle of Magnetic Clutch
The electromagnetic clutch of the automobile air conditioner is controlled by the air conditioner switch, thermostat, air conditioner controller, pressure switch, etc., to switch on or cut off the power transmission between the engine and the compressor when needed. In addition, when the car compressor is overloaded, it can also play a certain protective role.
Among them, the electromagnetic coil is fixed on the casing of the auto ac compressor, the drive disc is connected with the main shaft of the ac compressor, and the pulley is installed on the compressor headcover through a bearing and can rotate freely. When the air conditioner switch is turned on, the current passes through the electromagnetic coil of the electromagnetic clutch, and the electromagnetic coil generates electromagnetic attraction, which combines the drive plate of the ac compressor with the pulley, and transmits the torque of the engine to the compressor main shaft to rotate the compressor main shaft. When the air conditioner switch is turned off, the suction force of the electromagnetic coil disappears, the drive plate and the pulley are separated under the action of the spring sheet, and the compressor stops working.
The compressor pulley always rotates when the engine is running, but the compressor only runs when the pulley is engaged with the compressor drive shaft.
When this system is activated, current will flow through the solenoid coil. The current draws it to the armature plate. The strong magnetic force pulls the armature plate to the side of the steering pulley. This will lock the pulley and
The armature plates are together; the armature plates drive the compressor.
When the system is deactivated and current stops passing through the solenoid coil, the leaf spring pulls the armature plate away from the pulley.
The magnetic coil does not rotate because its magnetism is transferred to the armature through the pulley. The armature plate and the hub assembly are fixed on the compressor drive shaft. When the compressor is not driven, the clutch pulley rotates on the double-row ball bearings.
Malfunction Repair of Magnetic Clutch
When the air-conditioning electromagnetic clutch coil was burned, in addition to quality problems, the main reason is that the pressure of the car air-conditioning system is too high, and the resistance that drives the compressor to run is too large. The electromagnetic suction force of the electromagnetic coil exceeds the electromagnetic suction force of the electromagnetic coil, and it is burned by overheating.
There are 3 reasons for the high pressure of the auto air conditioning system:
1. The engine is running at idling speed when parking and the air conditioner is used under the sun for a long time;
2. When the cooling fan of the water tank fails, the air conditioner is still used for a long time and with high intensity (the cooling fan of the water tank is shared with the air conditioning condenser fan);
3. The amount of refrigerant gas added to the refrigeration system is excessive.
When the auto ac compressor starts to work, pay attention to the observation window of the liquid storage tank and find that there is no air bubble in the observation window. Then connect the high and low-pressure meter to the refrigeration system, check its pressure, and find that both the high-pressure side and the low-pressure side pressure deviate. Obviously, the refrigerant is overfilled. After the proper amount of refrigerant is removed from the low-pressure side (the pressure on the high-pressure side is 1.2-1.8MPa, and the pressure on the low-pressure side is 0.15-0.30MPa), the fault is eliminated.
In order to avoid such failures, the car air conditioner should not be used in the following 3 situations.
1. When the amount of refrigerant added exceeds the regulation, it must be discharged in time, otherwise, the air conditioner is not allowed to be used. The method to check the amount of refrigerant is: when the car ac compressor starts to work, check whether there are bubbles in the observation window of the liquid storage tank. Less, the refrigerant should be added in an appropriate amount,
2. When the cooling fan of the water tank fails and stops running, the air conditioner should be stopped immediately, otherwise, the refrigeration system will generate ultra-high pressure, which will cause the electromagnetic clutch to slip and burn.
3. When parking, when the engine is idling, it is best not to turn on the air conditioner.
How to repair magnetic clutch:
The magnetic clutch engages and disengages the compressor when your car's air conditioning is turned on and off. Once an electrical current from the on/off switch sends power to the magnetic coil, it causes the outboard clutch to pull in toward the compressor, locking up the pulley and engaging the compressor. Because the ac clutch is attached to the compressor shaft, if it becomes disengaged, it will not move the car ac compressor shaft. A few steps will help you remedy this problem.
Remove the car air conditioning accessory belt with the proper size wrench in your wrench set. Disconnect the connector on your compressor's magnetic coil. Use the right size socket to remove the 6 mm bolt in the center of the AC clutch.
Pull the clutch off, and observe the spacers on the shaft behind it. They are used to gap the clutch properly, so keep them in a safe place to avoid losing them. Remove the snap-ring on the shaft that secures the pulley, and slide this off the shaft.
Clean the shaft and other parts thoroughly before installation. Insert the new pulley, and engage the snap-ring with the beveled edge facing outward.
Install one spacer on the compressor shaft, then install the clutch, and fasten the 6 mm bolt securely.
Place the feeler gauge between the clutch and the pulley to ensure proper clearance. If the clearance is not correct, remove the clutch plate and add another spacer.
Check the air gap to ensure the clutch will engage properly. If the air gap and/or clearance are not accurate, your clutch might wear out more quickly. Adjoin the connector to the electromagnetic coil.
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Many new air conditioning systems and most new luxury cars use clutchless compressors equipped with compressor control valves. Clutchless compressors use thermistors, sensors, and solenoids to electronically perform the same functions as electromagnetic clutches mechanically.
The function of the valve is to balance the pressure of the fluid flowing through the system by controlling the angle of the swashplate. This keeps the evaporator at a constant temperature slightly above the freezing point to maximize the operating speed of the car's air conditioning system.
Although mechanical control valves still function in older and more economical cars due to the additional cost, the control range of electronic control valves is much superior. The electronic control valve is more efficient and reduces the displacement, reduces the wear of the AC system, reduces the engine load during operation, and produces cleaner emissions. Ultimately, the more expensive models are more cost-effective throughout the life cycle or vehicle.
Since the compressor control valve is electronic, the diagnostic test only needs to be connected to the diagnostic test equipment. Within a few minutes, you can determine whether your air conditioner compressor components are working properly.
Mechanical Control valve
High air conditioning demand
During periods of medium and high A/C demand, the system suction pressure will be greater than the control valve set point. During these periods, the control valve maintains bleed air from the crankcase to the suction port. Therefore, the crankcase pressure is same as the suction pressure. The angle of the wobble plate, so the compressor displacement is at its maximum.
Low air conditioning demand
During periods of low to medium A/C demand, the system suction pressure will drop to the control valve set point. The control valve maintains the exhaust from the exhaust to the crankcase and prevents the exhaust from the crankcase to the intake. The angle of the wobble plate and therefore the compressor displacement is reduced or minimized. During these periods, the displacement varies steplessly between approximately 5% and 100% of its maximum displacement.
Compressor control valve failure
(Only applicable to variable displacement compressors)
1. The valve is blocked by impurities (the evaporator is easy to freeze)
2. Improper setting of valve adjusting spring
1. Recover refrigerant from the air conditioning system.
2. Replace the displacement regulating valve located on the rear cover of the compressor.
3. Let the vacuum pump run for at least 15 minutes to exhaust non-condensable gas and moisture from the air conditioning system.
4. Return the recommended amount of refrigerant and the oil recovered with the refrigerant to the system.