Routine air conditioning refrigeration system inspection:

Cooling system balance pressure, low or high pressure measurement.

Current measurement, observe condensation and frost on gas and liquid valves, as well as the opening degrees of the two valves. Inspect the bending of the pipe through the wall opening, and whether the pipeline and wiring have been extended between the interior and exterior.

(1) If it's a three-phase control, make sure to adjust the phase sequence first.

(2) If there is no sound or indication, or if the sound is abnormal, upon plugging in or turning on, always check the power source. This includes the user's power source and the machine's power source. Some power sources are provided from outdoors to indoors, which may include transformers and wires.

(3) Check the working conditions of the CPU. The working conditions include +5V, reset (resistor-capacitor 4.8V, integrated 3V), replacement of crystal, and whether there is any leakage or short circuit in the peripheral circuit.

(4) Plugged in with sound, no sound, or receiver head failure.

(5) Plug-in, with an alarm sound, protection after several seconds; check for open circuit and short circuit in sensors, and open circuit in pressure switches, temperature switches, etc.