IV. Economizer Adjustment, Refrigerant Charge

III.OUTDOOR FAN ADJUSTMENT (Fig. 42)

1.Shut off unit power supply.

2.Remove outdoor-fan assembly (grille, motor, motor cover, and fan) and loosen fan hub setscrews.

3.Adjust fan height as shown in Fig. 42.

4.Tighten setscrews and replace outdoor-fan assembly.

UNIT	‘‘A’’
VOLTAGE	in.
208/230 V	2.75
460 V and 575 V	3.50

Fig. 42 — Outdoor Fan Adjustment

IV. ECONOMIZER ADJUSTMENT

Refer to Optional Economizer sections on pages 11 and 15.

IMPORTANT: Refer to Troubleshooting Tables 14-16 for addi- tional information.

V. REFRIGERANT CHARGE

A. Checking and Adjustment Refrigerant Charge

The refrigerant system is fully charged with R-22 refriger- ant, tested, and factory-sealed. Unit must operate in cooling mode a minimum of 10 minutes before checking charge.

NOTE: Adjustment of the refrigerant charge is not required unless the unit is suspected of not having the proper R-22 charge.

A superheat charging chart is attached to the outside of the service access panel. The chart includes the required suction line temperature at given suction line pressures and outdoor ambient temperatures.

An accurate superheat, thermocouple- or thermistor-type thermometer and a gage manifold are required when using the superheat charging method for evaluating the unit charge. Do not use mercury or small dial-type thermometers because they are not adequate for this type of measurement.

CAUTION: When evaluating the refrigerant charge, an indicated adjustment to the specified fac- tory charge must always be very minimal. If a substan- tial adjustment is indicated, an abnormal condition exists somewhere in the cooling system, such as insuf- ficient airflow across either coil or both coils.

Proceed as follows:

1.Remove caps from low- and high-pressure service fittings.

2.Using hoses with valve core depressors, attach low- and high-pressure gage hoses to low- and high- pressure service fittings, respectively.

3.Start unit in Cooling mode and let unit run until sys- tem pressures stabilize.

4.Measure and record the following:

a.Outdoor ambient-air temperature (F db).

b.Evaporator inlet-air temperature (F wb).

c.Suction-tube temperature (F) at low-side service fitting.

d.Suction (low-side) pressure (psig).

5.Using “Cooling Charging Charts” compare outdoor- air temperature (F db) with the suction line pressure (psig) to determine desired system operating suction line temperature. See Fig. 43-45.

6.Compare actual suction-tube temperature with desired suction-tube temperature. Using a tolerance of ± 3° F, add refrigerant if actual temperature is more than 3° F higher than proper suction-tube tem- perature, or remove refrigerant if actual temperature is more than 3° F lower than required suction-tube temperature.

B.To Use Cooling Charging Charts

Take the outdoor ambient temperature and read the suction pressure gage. Refer to appropriate chart to determine what the suction temperature should be. If suction temperature is high, add refrigerant. If suction temperature is low, carefully recover some of the charge. Recheck the suction pressure as charge is adjusted.

EXAMPLE: (Fig. 43)

Outdoor Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 F Suction Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 psig

Suction Temperature should be . . . . . . . . . . . . . . . . . . . . 49 F (Suction Temperature may vary ±5° F.)

C. Heating Mode Charge

Do not attempt to adjust charge by cooling methods while in Heating mode. When charging is necessary in Heating mode, recover refrigerant and weigh in according to unit data plate refrigerant data.

Fig. 43 — Cooling Charging Chart, 548D090

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548D specifications

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