What are the manifestations of insufficient refrigerant?

Performance of insufficient refrigerant:

① The tracheal valve is dry, and there is no obvious cool feeling when touched by hand. The reason is that the boiling end point in the evaporator is advanced due to insufficient refrigerant, which increases the superheat of the refrigerant in the valve and raises the temperature of the valve, which is higher than the dew point temperature of outdoor air.

② The valve of liquid pipe is frosted. The reason is that the pressure in the liquid pipe drops and the boiling point drops due to insufficient refrigerant, which makes the valve temperature lower than freezing point.

③ Open the panel of the indoor unit and remove the filter screen, and some evaporators may be found to be dewed or frosted. The reason is that due to the shortage of refrigerant, only some evaporators boil and absorb heat, which reduces the refrigeration area accordingly.

④ There is no thermal sensation in the exhaust air of outdoor unit. The reason is that the shortage of refrigerant leads to the decrease of condensation pressure and temperature, and the decrease of exhaust air temperature.

⑤ The drainage hose drains intermittently or does not drain at all. The reason is that the refrigerating area of evaporator decreases, the condensation area also decreases, and the amount of condensed water decreases.

⑥ The air and liquid valves of outdoor units have oil stains, and if there is oil stains, there will be leakage. The reason is that refrigerant and refrigeration oil have certain mutual solubility, fluorine escapes from the leak point and enters the atmosphere, while oil adheres to the leak point.

⑦ Measuring the working current of air conditioner is less than the rated current. The reason is that the compressor workload is reduced and the current is reduced due to insufficient refrigerant.

⑧ The pressure measured from the fluorine inlet of the outdoor unit is lower than 0.45Mpa. The reason is that the evaporation pressure drops due to insufficient refrigerant.