PREMIUM PRF047XW (01) PDF Document

To ensure safety during maintenance, you must obey the following basic attention:

1) During service:

• Pay attention to the flame or ignition nearby, particularly after welding using gas too. You must turn off the flame first, then you can do other maintenance work, because the refrigerant will produce toxic air when it touches flame, sparkle or a capacitor.

• Do not do the welding work in an airtight or bad air circulation room.

• When discharging the refrigerant, you must keep the room in a good air circulation condition.

• When cutting the suction pipe or discharging pipe of the compressor, pay attention to the surplus refrigerant and internal pressure in the cooling system pipe.

2) Unplug the unit:

• When you are ready to proceed with maintenance, you must first unplug the freezer to ensure safety.

3) Avoid electrical shock:

• Normally when proceeding with maintenance, you must open the power supply first. But if you must check the field wiring or a component of the unit with the power supply on, you must be very careful and not touch the live parts. If you find out the wiring is aged, please replace it in time.

4) Correct use of components:

• If a component is damaged and needs to be replaced, be sure to replace it with a component of the same model. Do not use other models or other brand components, and do not use a changed component.

5) Correct use of service tools:

• Ensure to use the appropriate service tool right. Otherwise it will cause bad electrical contact or loose fixing, and an incidence will happen.

6) Wiring connection:

• When re-connecting a cut wire, be sure to use a soldering method or terminal connection, and then wrap the connection point with insulation tape to ensure a good connection.

7) Insulation resistance measure:

• After completing the service and assembly, you must use a multi-meter to measure the insulation resistance. If it is greater than 1 million ohm, then you can plug in the unit.

8) Grounding test:

• After maintenance, use a multimeter to measure the grounding resistance to ensure the grounding resistance is less than 0.1 ohm.

9) Pay attention to children or infants nearby:

• When performing maintenance, don’t let a child or an infant be nearby.

10) Cleaning:

• After service, do the necessary cleaning work and tell the customer the necessary precautions.

Please note, some units are without the RUNNING CAPACITOR marked in red color in the diagram, according to the used compressor model.

The refrigerant flows through the system in the following order:

1. Compressor

2. Condenser

3. Dry Filter

4. Capillary

5. Evaporator

6. Air Suction Pipe

7. Back to the Compressor

The arrows in the system diagram indicate the flowing direction of the refrigerant.

When replacing components, you must unplug the unit first for safety.

Unscrew the fixing screw of the thermostat box, remove the thermostat box, then remove the old thermostat. Install the new thermostat of the same model, and reinstall back the whole thermostat box with the same fixing screw.

When replacing components, you must unplug the unit first for safety.

Remove the clamp of the connecting terminal cover of the compressor and the terminal cover. Toward the vertical direction, remove the broken-down starter or overload protector, install back the new starter or overload protector, then fix back the terminal box cover and its clamp.

When replacing components, you must unplug the unit first for safety.

Remove the old door gasket seal from the groove of the door liner, then install the new gasket seal into the four sides of the groove. Install it as evenly as possible. Open and close the door several times to ensure that the door is sealed.

When replacing components, you must unplug the unit first for safety.

(a) First, cut the welding point of the technical pipe of the compressor to discharge the refrigerant inside the cooling system. Then weld the old point to disconnect the pipe to the compressor, remove the compressor to replace with a new one. Pay attention to replace with a new refrigerant dry filter.

(b) Install the new compressor, weld the high pressure side and low pressure side pipe to the compressor, and check the system for leakage. After completing a vacuum on the cooling system, charge the correct amount of refrigerant into the system from the low pressure side pipe. After this, run the unit to check if the cooling performance is ok or not, then weld and close the technical pipe.

If there is no frost, you should perform leakage detecting.

A) If a leakage point is found, first cut off the low pressure pipe to discharge the remaining refrigerant in the system. Then clean the pipe, replace it with a new dry filter, and weld again. Recharge the refrigerant and perform leakage detection again.

B) If a leakage point cannot be found, cut off the low pressure pipe. If there is no refrigerant coming out, then recharge the refrigerant and perform leakage detection again. If there is refrigerant coming out, cut off the high pressure pipe (this means that compressor suction is normal) and charge the condenser pipe with pressurized nitrogen. If no air comes out at the low pressure side, it means the pipe is blocked; replace the blocked parts and clean the system pipe. If there is no air suction at the compressor low pressure side, cut off the high pressure pipe; this means the air compression of the compressor is not good, so please replace the compressor.

First, perform leakage detection.

A) If the leakage point is confirmed, cut off the low pressure pipe. If a little refrigerant air spurts out, it means that the system leaks slowly at the leakage point. You should repair the welding of the cut pipe and the leakage point, and clean the system pipe with high pressure nitrogen. Replace the dry filter, and after completing this work, re-vacuum and recharge the refrigerant. Finally, perform leakage detection again.

B) If a large quantity of refrigerant spurts out, cut off the high pressure pipe to check if the suction of the compressor low pressure pipe is normal. If there is no suction or weak suction, it means there is not good compression, and you need to replace the compressor. If the suction is normal, then charge the clean and warm nitrogen to the condenser pipe. If you find the returned nitrogen from the low pressure side is not sufficient, it means the system pipe is clogged lightly; please replace the clogged parts and clean the pipe.

Check the temperature of the high pressure side pipe and the compressor. You will find it is too high. Then check the low pressure pipe with frost. If this is the case, it means there is too much refrigerant in the system. Please recharge with the appropriate quantity of refrigerant once more.

The unit working discontinuously may indicate that the system is clogged with ice. Please replace the dry filter and clean the system with clean and warm nitrogen.

Please check the electrical parts, such as the PTC starter, capacitor, overload protector, thermostat, etc. If you find that the parts are malfunctioning, then replace them with a new one of the same type and specification. If all of these parts are good, please measure the resistance of the compressor winding. If the resistance is abnormal, you must replace the compressor. Otherwise, check if the overload protector is activated. If it is, it means there is an overly large current and the compressor is malfunctioning, so you should also replace the compressor.

If the frost thickness is greater than 5mm, it indicates that the frost is too thick, which can be due to incorrect usage.

If there is condensed water on the closure, it is because the environment is too wet, which means the relative humidity is too high.

Because refrigerant R134a and its lubricating oil grease have strong water absorbability and oxidation ability, and will cause catalysis reactivity with chloride to produce impurity to be silt, you should pay more attention to the water quantity, oxide quantity, chloride quantity, oil quantity and impurity quantity in the cooling system, and control it more strictly.

Left water quantity control:

a) If the cooling system parts, like condenser, evaporator, compressor, or the dry filter etc., need to be replaced, the replaced parts should be stored charging with dry nitrogen with pressure 0.2~0.3Mpa. If these parts have leakage of nitrogen, they must be dried in a high temperature chamber and be taken out of the water before using.

b) The molecular dry desiccant inside the dry filter must be controlled strictly, guaranteed that the left water quantity must be lower than 1.5WT%. Normally, after the dry filter is opened from its vacuum package, it must be welded to the pipe system within 5 minutes. In a wet condition (relative humidity>50%), you must take measures to be protected from humidity, and the dry filter must be connected to the system pipe at once after removing it from its package, so as to produce a sealing system.

1) No need for recycling equipment, except for a charging machine. If the equipment is special for the R134a refrigerant system, you must mark it clearly to avoid using it with other refrigerants (except for welding machine, pliers, electronic balance).

2) The vacuum machine and charging machine are special and should be used only for the R134a refrigerant system.

Special requirement during service process:

(a). The duration from opening the compressor to the vacuuming process must be less than 10 minutes, and for other parts, not more than 12 minutes.

(b). The vacuuming duration should not be less than 20 minutes.

(c). If refrigerant leakage happens, it is necessary to replace the compressor. Before welding, dry the cooling system with nitrogen air.

(d). If a dust blockage happens in the cooling system pipe, if it can be blown out by the nitrogen, you don’t need to replace the compressor; otherwise, the cabinet is not useful (and the evaporator is not useful).

(e). If an ice blockage happens in the system pipe, you must replace the compressor.

(f). Change the dry filter only if the system is opened.

Main point of service:

1. The replaced compressor must be returned back to the compressor manufacturer to be treated.

2. The compressor can’t be tested through direct absorbing atmosphere; it will damage the compressor.

3. If the system pipe is opened for a long time or leakage happens, you can dry the system by nitrogen during service.

4. All of the welding material must be protected from wet conditions. And ensure to use as little as enough as possible.

5. Check if the compressor is pressurized or not when opening.

6. When storing the R134a refrigerant, you must keep it sealed and not in contact with the atmosphere directly.

After completing the service, it normally needs to be test run for 1-2 days. When proved to be safe and have good cooling performance, then move it to the customer or user. During test running, we suggest that you perform the following items:

1) Insulation and safety:

Before plugging in, use the DC 500 meg-ohm meter to measure the insulation resistance between the live parts and dead metal enclosure, ensuring the result is not lower than 1 meg-ohm.

2) Starting capability:

The compressor should start smoothly, and can start or stop normally. If the unit can’t start or stop normally, you must find the root cause and delete the cause, then you can plug it in to let it run.

3) Cooling performance:

After running for 24 hours, check that the frost on the surface of the cabinet liner is even, and there is no frost on the suction pipe.

4) Electrical structure and safety:

After service, check all of the electrical parts, ensure the connection terminal of the electrical parts don’t loose and the grounding wire is ok.

5) Leakage checking:

After running for 24 hours, check one by one of the welding points by using a halogen leakage detecting device or suds. If leakage happens again, then it should be serviced again.