Sunbeam 20060328, Руководство по обслуживанию

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REFRIGERANT CYCLE
The refrigerant cycle is continuous and takes place every time the compressor functions. When the refrigerant passes
through the evaporator it changes state (from liquid to gaseous), due to the heat entering the cabinet through its isolated
walls and the heat because of stored products and the times the door is opened. Then, vapor is extracted from the
evaporator through the suction line and taken to the compressor. Compressure increases pressure in the compressor, as
well as the vapor temperature, which is then forced to pass through the discharge valve to the discharge line and to enter
the condenser. The air passing over the condenser surface dissipates heat of the high-pressure vapor that is then
condensed and changed to the liquid state. The liquid refrigerant flows from the condenser to the evaporator through the
liquid line (capillary tube). Before entering the evaporator, it is sub cooled in the heat interchanger by the low temperature
suction vapor in the suction line.
LOSS IN THE LOW PRESSURE SIDE OR HIGH PRESSURE SIDE, OR DEFICIENT LOAD
A loss of refrigerant may cause the following situations: the compressor works longer or constantly; works a long time o
constantly; the compartment freezer temperature is higher than normal; the evaporator is partially frosted (depending on
the refrigerant volume of loss); a compartment fridge temperature lower than normal; low suction pressure (vacuum);
and low power. The condenser will be from “warm to fresh”, in this case depending on the loss volume.
By adding refrigerant, the frost configuration will improve, the suction and discharge pressures will increase, the
condenser will heat and the power will grow.
In case of refrigerant loss in the low-pressure side causing total loss of refrigerant, the compressor will work but without
refrigeration. The suction pressure will lower under the atmospheric pressure, and air and humidity will enter the system,
thus saturating the drying filter.
If the indications show lack of refrigerant and no loss is found after a deep test, the load can be corrected without a
compressor change.
If it is considered that the system has worked a long time without refrigerant and the loss occurred in the evaporator, an
excessive quantity of humidity might have entered the system, and the compressor will possibly be replaced to avoid
new repairs.
If a loss is found in the high-pressure side and some refrigerant remains in the system, it is not necessary to replace the
compressor.
TESTS TO FIND REFRIGERANT LEAKAGE
If the system needs more refrigerant and has not been opened recently, it might have a leakage.
Adding refrigerant without first locating and repairing the leakage or replacing the element will not correct the problem
permanently.
THE LEAKAGE MUST BE FOUND. Enough refrigerant might have escaped and caused restrain for an
efficient test to find leakages. In this case, a 6.35 mm (1/4”) line-penetrating valve should be added to the compressor
process tube. Add enough refrigerant to increase pressures to 10.9 kPa. Through this procedure, it is easier to fin small
loss before discharging the system.
NOTE: Remove the penetrating valve after locating the loss, and change the refrigerant.
HOW TO CHECK INTERNAL LEAKAGE (ANTI - CONDENSATION TUBE)
Before checking if there is internal leakage, verify all the system accessible elements and joints to find out if they have
leakages.
To confirm suspicion of anti – condensation internal leakage, use the following procedure:
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