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16
7.0 CHECKING REFRIGERANT CHARGE
Charge for all systems should be checked against the Charging Chart inside the
access corner panel or Charging by weight.
IMPORTANT:Do not operate the compressor without charge in system. Additio n of
R - 410A will raise pressures (suction, liquid and discharge).
7.1 CHARGING BY LIQUID PRESSURE
In order to properly charge the system, the following conditions must be met:
1) Outdoor temperature above 60°F.
2) Indoor temperature between 70°F to 100°F.
3) Installation must be complete with brazed joints and drier visually inspected.
4) The unit electrical installation must be checked and unit powered for one (I) hour if
crank case heater is used or five (5) minutes if no crankcase heater is used.
Follow these steps:
1. Run in Force cooling mode(click the FORCE button in cooling mode )at least 20
minutes.
2. Measure OUTDOOR AMBIENT TEMPERATURE within 6 inches of coil.
3. Measure SUCTION LINE PRESSURE AND TEMPERATURE.
4.According to the superheat of suction line, confirm that the TXV is working
properly(Usually the superheat is between 10 to 15 ). If not, it should be adjusted.
5. Find the TARGET LIQUID PRESSURE at the intersection between the SUCTION
LINE PRESSURE and the OUTDOOR AMBIENT TEMPERATURE, if falls between
rows or columns then estimate the TARGET LIQUID PRESSURE or SUCTION LINE
PRESSURE falls between rows or columns then estimate the TARGET LIQUID
PRESSURE between the rows and columns.
5. Compare the measured LIQUID LINE PRESSURE to the TARGET LIQUID
PRESSURE, add charge to raise the pressure or recover charge to lower it.
6. After running unit for 10 minutes if the SUCTION LINE PRESSURE changes, go
back to step 2 otherwise remove test equipment and cover the valves.
7.2 CHARGING BY WEIGHT
For a new installation,evacuation of interconnecting tubing and indoor coil is adequate;
otherwise,evacuate the entire system. The factory refrigerant charge in the outdoor
unit is sufficient for 15 feet of standard size interconnecting liquid line. Calculate
actual charge required with installed liquid line size and length,please see 4.1 of
instruction.
With an accurate scale (+/- 1 oz.) adjust charge difference between that shown on
the unit data plate and that calculated for the new system Installation. if the entire
system has been evacuated, add the total calculated charge.
7.3 FINAL LEAK TESTING
After the unit has been properly evacuated and charged, a halogen leak detector
should be used to detect leaks in the system. All piping within the condensing unit,
evaporator, and interconnec ting tubing should be checked for leaks. If a leak is
detected, the refrigerant should be recovered before repairing the leak. The Clean Air
Act prohibits releasing refrigerant into the atmosphere .
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