York YS Service Manual download pdf (Page 46)

3. Open the oil charging valve and pump oil into the

system until oil level in the oil separator is about

midway in the upper sight glass. Then, close the

charging valve and disconnect the hand oil pump.

4. As soon as oil charging is complete, close the

power supply to the starter to energise the oil

heater. This will keep the concentration of

refrigerant in the oil to a minimum.

Draining the oil

1. If the oil draining is to restore the correct oil level the

unit may be kept in operation. If the oil charge is

being replaced the unit must be shut down and the

supply switched off to prevent operation of the oil

heater.

2. If possible run the unit at full load for a short period

to recover most of the oil in the system to the oil

separator.

3. Drain the oil into a suitable container from the oil

charging valve on the bottom of the oil separator.

4. Dispose of old oil according to local regulations for

the disposal of oily wastes.

7.6 Refrigerant Charge

The refrigerant system is pressure tested and

evacuated at the factory.

7.6.1 Checking The Refrigerant Charge

The refrigerant level should have been observed

and the level recorded after initial charging. With

the correct charge the level should visible in the

sight glass.

The refrigerant charge should always be

checked and trimmed when the system is shut

down.

The refrigerant charge level must be checked after the

pressure and temperature have equalised between the

condenser and cooler. This would be expected to be 4

hours or more after the compressor and water pumps

are stopped.

7.6.2 Leak Testing

After the system has been charged, the system should

be carefully leak tested with a R134a compatible leak

detector to ensure all joints are tight.

If any leaks are indicated, they must be repaired

immediately. Usually, leaks can be stopped by

tightening flare nuts or flange bolts. However, for any

major repair, the refrigerant charge must be removed.

7.6.3 Vacuum Testing

Vacuum testing should be conducted as follows:

1. Connect a high capacity vacuum pump, with

indicator, to the system charging valve and start the

pump.

2. Open wide all system valves. Be sure all valves to

the atmosphere are closed.

3. Operate the vacuum pump until a wet bulb

temperature of 0°C or a pressure of 5 mm Hg

(absolute) is reached.

4. To improve evacuation circulate warm water (not to

exceed 50°C) through the cooler and condenser

tubes to thoroughly dehydrate the shells. If a

source of hot water is not readily available, a

portable water heater should be employed. DO

NOT USE STEAM. A suggested method is to

connect a hose between the source of hot water

under pressure and the cooler head drain

connection, out the cooler vent connection, into the

condenser head drain and out the condenser vent.

To avoid the possibility of causing leaks, the

temperature should be brought up slowly so that

the tubes and shell are heated evenly.

5. Close the system charging valve and the stop valve

between the vacuum indicator and the vacuum

pump. Then disconnect the vacuum pump leaving

the vacuum indicator in place.

6. Hold the vacuum in the system for 8 hours; the

slightest rise in pressure indicates a leak or the

presence of moisture, or both. If, after 8 hours the

wet bulb temperature in the vacuum indicator has

not risen above 4.4°C or a pressure of 6.3 mm Hg,

the system may be considered tight.

Be sure the vacuum indicator is valved off while holding

the system vacuum and be sure to open the valve

between the vacuum indicator and the system when

checking the vacuum after the 8 hour period.

7. If the vacuum does not hold for 8 hours within the

limits specified, the leak must be found and

repaired.

7-4 035L02381-GB0

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York YS Service Manual Page 46

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