Haier RF-8888-193 Compressor suddenly stops, Air in the system Analysis of Trouble, Remedy

Remedy

It is quite difficult to differentiate this trouble from others because they have similar symptoms. When repairing, listen attentively for abnormal sounds coming from the compressor. Oftentimes, broken pieces of valve block strike against the cylinder. Check to see if the compressor casing is too hot. Secondly, measure the pressures at the high and low-pressure ports of the compressor with pressure gauges. If the gas suction valve block is broken, the suction pressure gauge pointer will swing violently and the suction pressure will be very high. Whereas when the gas discharge valve block is broken, the discharge pressure gauge pointer will swing drastically and the discharge pressure will be very high. In both cases, stop the compressor at once. If possible, open the cylinder cover, check the valve block, and repair it.

Compressor suddenly stops

Very often, when the compressor suddenly stops, the gas suction pressure and/or discharge pressure have exceeded their respective prescribed ranges. When this happens, the pressure-operated protective relay automatically shuts off the power to the compressor. Below we discuss the reasons for high gas discharge pressure and low suction pressure.

Stoppage due to excessively high gas discharge pressure

1) High gas discharge pressure due to excess refrigerant

Analysis of Trouble

Loose frosting and poor refrigerating effect may occur if excessive refrigerant has been charged into the system. Excess refrigerant will occupy additional space in the evaporator. This will reduce its heat dissipating area, and the phenomenon of “liquid striking” may occur. Condensation may occur on the gas return tube, and the gas discharge pressure will rise. When it reaches the threshold value, the protective relay will actuate and shut off the power supply to the compressor.

Remedy

Open the tubing. Re-evacuate and charge the system with a proper quantity of refrigerant.

2) Air in the system

Analysis of Trouble

The residual air in the system will circulate with the refrigerant in the system. The major symptoms are higher gas discharge pressure, higher discharged gas temperature, and poor refrigerating effect. The gas discharge pressure will exceed its maximum value when the compressor has run for an extended period, and activates the protective relay.

Remedy

Check the air has been in the refrigerating system. Generally, there are three possibilities. First, is that the air has been sucked into the system during repairs due to carelessness. Secondly, it has not been completely purged evacuating the system. The third possibility is that there are leak points at the low-pressure end of the refrigerating system. Leak points appear in low temperature parts or assemblies. This is because the evaporation temperature is lower for such low temperature devices, especially at the low-pressure end; it is easier for the air to go into the system. Once it has been ascertained that air does exist

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