pressure controllerIt is an electrical controller controlled by pressure signals, which means that when the discharge pressure of the compressor in the air conditioning unit exceeds the set value or the suction pressure is lower than the set value, the electrical contacts of the pressure relay cut off the control signal power supply, causing the compressor to stop working, playing a protective and automatic control role.
When detecting the pressure controller, the control principle and structural principle of the pressure switch can be used to detect it in a disconnected or connected state with the refrigeration system:
1. Detection after disconnecting the refrigeration system
Under atmospheric pressure, the low-pressure switch is tested by measuring its two terminals with a multimeter in resistance mode. Normally, it should be disconnected. If it is in a short circuit state, it indicates that the pressure switch is damaged.
The detection method for high-pressure switches is also the same, the difference is that under normal pressure, the two wiring terminals should be short circuited normally, and disconnected in case of a fault.
2. Testing after connecting the refrigeration system
1) Shutdown status detection
When the air conditioner is turned off, the system is in a balanced state with a pressure of around 1.0MPa (gauge pressure). Under this pressure state, the wiring terminals of both high and low pressure switches should be in the connected state. If the resistance range of the multimeter is used to measure and it is found to be in the disconnected state, it indicates that the pressure switch is damaged.
2) Power on status detection
Firstly, check the circuit and eliminate any issues with the control circuit. After confirming that the circuit is normal, short-circuit the pressure switch. If the refrigeration is running normally and the pressure is within the normal range, it indicates that the pressure switch has malfunctioned.