Daikin EWAD620-C17C-SL, Service Manual, Page: 299 / 304

ESIE10-01 Maintenance
Part 5 – Maintenance 5–9
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N.B.: As the load changes and the number of active fans changes, subcooling also changes and
takes a few minutes to stabilise. In any case, it must never go below 3°C in any condition.
Furthermore, the subcooling value may change slightly as the water temperature and suction
superheating vary.
One of the two following scenarios can arise in a machine without refrigerant:
1. If the refrigerant level is slightly low, the flow of bubbles can be seen through the liquid sight
glass. Replenish the circuit as described in the replenishment procedure.
2. If the gas level in the machine is moderately low, the corresponding circuit could have some low
pressure stops. Replenish the corresponding circuit as described in the replenishment proce-
dure.
Refrigerant
replenishment
procedure 1. If the machine has lost refrigerant, it is necessary to first establish the causes before carrying out
any replenishment operation. the leak must be found and repaired. Oil stains are a good indica-
tor, as they can appear in the vicinity of a leak. However, this is not necessarily always a good
search criterion. Searching with soap and water can be a good method for medium to large
leaks, while an electronic leak detector is required to find small leaks.
2. Add refrigerant to the system through the service valve on the evaporator inlet pipe.
3. The refrigerant can be added under any load condition between 25 and 100% of the circuit. Suc-
tion superheating must be between 4 and 6°C.
4. Add enough refrigerant to fill the liquid sight glass entirely so that no flow of bubbles can be seen
any more. Add an extra 2 ÷ 3 kg of refrigerant as a reserve, to fill the subcooler if the compressor
is operating at 50 - 100% load.
5. Check the subcooling value by reading the liquid pressure and the liquid temperature near the
expansion valve. The subcooling valve must be between 4 and 8°C and 10 and 15°C for the
machines with economiser. The subcooling value will be lower at 75 - 100% load and greater at
50% load.
6. With ambient temperature higher than 16°C, all fans must be on.
7. Overcharging the system will cause a rise in the compressor's discharge pressure, due to
excessive filling of the condensation section tubes.
Pressure/Temperature table of the HFC-134a
°C Bar °C Bar °C Bar °C Bar
-14 0.71 12 3.43 38 8.63 64 17.47
-12 0.85 14 3.73 40 9.17 66 18.34
-10 1.01 16 4.04 42 9.72 68 19.24
-8 1.17 18 4.37 44 10.30 70 20.17
-6 1.34 20 4.72 46 10.90 72 21.13
-4 1.53 22 5.08 48 11.53 74 22.13
-2 1.72 24 5.46 50 12.18 76 23.16
0 1.93 26 5.85 52 13.85 78 24.23
2 2.15 28 6.27 54 13.56 80 25.33
4 2.38 30 6.70 56 14.28 82 26.48
6 2.62 32 7.15 58 15.04 84 27.66
8 2.88 34 7.63 60 15.82 86 28.88
10 3.15 36 8.12 62 16.63 88 30.14