Cooling temperature control
The main components of the system are the evaporator temperature sensor, the air conditioner controller and the associated circuits. When the evaporator temperature changes, the sensor resistance changes accordingly, an electrical voltage signal corresponding to the current temperature is transmitted to the air conditioner controller, then the signal is amplified in the controller amplifier circuit, which controls the operation of the electromagnetic clutch relay. When the electromagnetic clutch relay is on, the electromagnetic clutch engages and the compressor starts to operate, while the temperature drops. When the relay is turned off, the electromagnetic clutch disengages, the compressor stops, and the temperature rises. The air conditioning control system controls the operation of the compressor, maintaining the cooling temperature within a specified range.
Compressor
An engine with an electronic fuel injection system controls the compressor operation according to the engine load under certain special conditions.
The compressor switches off when the engine starts, when driving, when accelerating sharply, or when the engine speed is too high.
Protection system
The system ensures normal operation of the air conditioning system, regulates the pressure and temperature in the system using the pressure switch in the dryer and the evaporator temperature sensor, and also performs protective functions. The system's functions include:
- 1. Low pressure protection: When the pressure is lower than 0.196±0.02MPa, the pressure switch is turned off, the rotation is not transmitted to the compressor clutch, and the compressor stops.
- 2. High pressure protection: when the pressure exceeds 3.14+0.02MPa, the pressure switch turns off, the rotation is not transmitted to the compressor clutch, and the compressor stops.
- 3. High pressure control: When the pressure exceeds 1.77±0.1MPa, the pressure switch closes, a corresponding signal is transmitted to the engine control unit, resulting in an increase in the rotation speed of the cooling fan.
- 4. Low temperature protection: When the evaporator temperature sensor detects the temperature below 5°C, the compressor clutch is released and the compressor stops.
- 5. High temperature protection: If the evaporator temperature sensor detects a temperature higher than 125°C, the compressor overheat protection will be activated and the compressor will stop.