Method for judging whether the amount of refrigerant is suitable
1 The phenomenon of insufficient refrigerant
①The suction pressure and discharge pressure of the compressor are lower than those in normal operation.
②The cooling capacity decreases, and the cooling effect is poor.
③On the liquid display glass of the liquid supply pipe, it can be seen that air bubbles or foam-like objects flow through intermittently.
④The wall hissing sound can be heard at the thermal expansion valve, and its loudness is higher than usual.
⑤There is little condensation or frost on the thermal expansion valve, and when the opening of the expansion valve is increased, the suction pressure still does not rise.
2 The phenomenon of too much refrigerant when too much refrigerant
①In a refrigeration system without a liquid accumulator, the condensing pressure will increase, because the refrigerant liquid floods a part of the condensing surface area, and the efficiency of the condenser decreases.
②In the system with accumulator, the liquid level in the accumulator exceeds 2/3 of the height of the sight glass.
③Although the liquid level in the accumulator is not high, the opening of the expansion valve is too large, which will cause too much liquid to enter the evaporator, the evaporation pressure will rise, the compressor will be seriously frosted, and even "cylinder flushing" will occur.
Too much or too little refrigerant in the system will make the system unable to operate normally, and the refrigerant must be discharged or supplemented.
Refrigerant emissions
When the refrigerant is discharged, the surrounding environment must be well ventilated and not close to an open flame, otherwise toxic gas will be produced.
1. Close the high and low pressure manual valves on the manifold pressure gauge, connect the high and low pressure hoses to the compressor high and low pressure inspection valves respectively, and place the free end of the intermediate pipe on the working cloth.
2. Slowly open the high-pressure manual valve to allow the refrigerant to be discharged from the intermediate hose. The valve cannot be opened too much, otherwise the refrigeration lubricating oil in the compressor will flow out with the refrigerant.
3. When the pressure gauge reading drops below 0.35MPa, slowly open the manual valve to discharge the refrigerant from high and low pressure at the same time.
4. Observe the reading of the pressure gauge. As the pressure drops, gradually open the high and low pressure manual valve until the reading of the high and low pressure gauge indicates zero.
Refrigerant filling
1. High-pressure side filling
The bypass hole (multi-purpose channel) of the compressor discharge valve (high pressure valve) is filled with refrigerant liquid. Its characteristics are safe and fast, and it is suitable for the first filling of the refrigeration system, that is, the system filling after leak detection and vacuuming. However, when using this method, it must be noted that the compressor cannot be turned on during filling (the engine is stopped), and the refrigerant tank is required to be upside down
Steps:
1) When the system is evacuated, close the high and low pressure manual valves on the manifold pressure gauge.
2) Connect one end of the intermediate hose to the connector of the refrigerant tank injection valve, open the refrigerant tank opening valve, and then unscrew the nut at one end of the manifold pressure gauge hose, let the gas overflow for a few minutes, and then tighten the nut.
3) Unscrew the high-pressure side manual valve to the fully open position, and turn the refrigerant tank upside down.
4), inject a specified amount of liquid refrigerant from the high pressure side. Close the refrigerant tank fill valve and the high-pressure manual valve on the manifold pressure gauge, then remove the gauge. When the system is filled with refrigerant from the high pressure side, the engine is not started (compressor stops), do not unscrew the low pressure manual valve on the manifold pressure gauge to prevent hydraulic shock.
2. Low pressure side filling
Filling from the bypass hole (multi-purpose channel) of the compressor suction valve (low pressure valve) is filled with refrigerant gas, which is characterized by a slow filling speed and can be used when the system is supplemented with refrigerant.
Steps
1) Connect the manifold pressure gauge to the compressor and refrigeration tank.
2) Open the refrigerant tank, loosen the nut of the middle injection hose on the manifold pressure gauge, until you hear the sound of refrigerant vapor flowing, and then tighten the nut. This expels the air injected into the hose.
3) Close the manual high-pressure valve, stand the refrigerant cylinder upright, start the engine, make the air-conditioning compressor run, open the low-pressure manual valve, and let the gaseous refrigerant enter the compressor from the low-pressure side. When the pressure value of the system reaches 0.4MPa, close the Low pressure manual valve and refrigerant tank switch valve.
4), start the engine, turn on the air conditioner switch, and adjust the blower switch and temperature control switch to the maximum.
5) Open the manual valve on the manifold pressure gauge to let the refrigerant continue to enter the refrigeration system until the filling amount reaches the specified value.
6) After adding the specified amount of refrigerant to the system, observe from the sight glass to confirm that there are no air bubbles and excess refrigerant in the system. Then adjust the engine speed to 2000r/min, and open the air volume of the cold blower to the highest gear. If the temperature is 30-35℃, the pressure on the low-pressure side in the system should be 0.147-0.192MPa, and the pressure on the high-pressure side should be 1.37-1.67MPa.
7) After filling, close the low-pressure manual valve on the manifold pressure gauge, close the injection valve installed on the refrigerant tank, stop the engine, remove the manifold pressure gauge from the compressor, and act when unloading Be quick to avoid excessive refrigerant leakage.
