Carrier 50SS018-060, 50SX024-060 owner manual Start-Up Cooling Section and Make Adjustments

4.If the unit is equipped with a crankcase heater, start the heater 24 hours before starting the unit. To start the heater only, turn the thermostat to the OFF position and ener- gize the electrical disconnect to the unit.

START-UP

Use the Start-Up Checklist supplied at the end of this book, and proceed as follows:

Check for Refrigerant Leaks Ð Locate and repair refrigerant leaks and charge the unit as follows:

1.Using both high- and low-pressure ports, locate leaks and reclaim remaining refrigerant to relieve system pressure.

2.Repair leak following accepted practices.

NOTE: Install a ®lter drier whenever the system has been opened for repair.

3.Check system for leaks using an approved method.

4.Evacuate refrigerant system and reclaim refrigerant if no additional leaks are found.

5.Charge unit with R-22 refrigerant, using a volumetric- charging cylinder or accurate scale. Refer to unit rating plate for required charge. Be sure to add extra refrigerant to compensate for internal volume of ®lter drier.

Start-Up Cooling Section and Make Adjustments

Complete the required procedures given in the Pre- Start-Up section page 25 before starting the unit.

Do not jumper any safety devices when operating the unit.

Do not operate the compressor when the outdoor tem- perature is below 40 F (unless accessory low-ambient kit is installed).

Do not rapid-cycle the compressor. Allow 5 minutes be- tween ``on'' cycles to prevent compressor damage.

CHECKING COOLING CONTROL OPERATION Ð Start and check the unit for proper cooling control operation as follows:

1.Place room thermostat SYSTEM switch in OFF position. Observe that blower motor starts when FAN switch is placed in ON position and shuts down when FAN switch is placed in AUTO. position.

2.Place SYSTEM switch in COOL position and FAN switch in AUTO. position. Set cooling control below room tem- perature. Observe that compressor, condenser fan, and evapo- rator blower motors start. Observe that cooling cycle shuts down when control setting is satis®ed.

3.When using an automatic changeover room thermostat, place both SYSTEM and FAN switches in AUTO. posi- tions. Observe that unit operates in Cooling mode when temperature control is set to ``call for cooling'' (below room temperature).

IMPORTANT: Three-phase, scroll compressors in the 50SS048,060 and 50SX036-060 units are direction-oriented. These units must be checked to ensure proper compressor 3-phase power lead ori- entation. If not corrected within 5 minutes, the in- ternal protector will shut off the compressor. The 3-phase power leads to the unit must be reversed to correct rotation. When turning backwards, scroll com- pressors emit elevated noise levels, and the differ- ence between compressor suction and discharge pressures may be dramatically lower than normal.

CHECKING AND ADJUSTING REFRIGERANT CHARGE

ÐThe refrigerant system is fully charged with R-22 refrig- erant, and is tested and factory sealed.

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 label is attached to the outside of the compressor access door. The label includes a ``Superheat Charging Table'' and a ``Required Suction-Tube Tempera- ture (F)'' chart.

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

When evaluating the refrigerant charge, an indicated ad- justment to the speci®ed factory charge must always be very minimal. If a substantial adjustment is indicated, an abnormal condition exists somewhere in the cooling system, such as insufficient air¯ow across either coil or both coils.

Proceed as follows:

1.Remove caps from low- and high-pressure service ®ttings.

2.Using hoses with valve core depressors, attach low- and high-pressure gage hoses to low- and high-pressure serv- ice ®ttings, respectively.

3.Start unit in cooling mode and let unit run until system pressures stabilize.

4.Measure and record the following:

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

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

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