Carrier 50HS018 Installation, Start-up And Service Instructions Manual

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Contents

START-UPUse the Start-Up Checklist supplied at the end of this book,and proceed as follows:Check for Refrigerant Leaks — Locate and repairrefrigerant leaks and charge the unit as follows:1. Using both high- and low-pressure ports, locate leaks andreclaim remaining refrigerant to relieve system pressure.2. Repair leak following accepted practices.NOTE: Install a filter drier whenever the system has beenopened for repair.3. Check system for leaks using an approved method.4. Evacuate refrigerant system and reclaim refrigerant if noadditional leaks are found.5. Charge unit with R-22 refrigerant, using a volumetric-charging cylinder or accurate scale. Refer to unit ratingplate for required charge. Be sure to add extra refrigerantto compensate for internal volume of filter drier.Unit Start-Up AdjustmentsComplete the required procedures given in the Pre-Start-Up section page 17 before starting the unit.Do not jumper any safety devices when operating theunit.Do not operate the unit in Cooling mode when theoutdoor temperature is below 40 F (unless accessory low-ambient kit is installed).Do not rapid-cycle the compressor. Allow 5 minutesbetween ‘‘on’’ cycles to prevent compressor damage.CHECKING COOLING AND HEATING CONTROL OP-ERATION — Start and check the unit for proper control op-eration as follows:1. Place room thermostat SYSTEM switch in OFF position.Observe that blower motor starts when FAN switch is placedin ON position and shuts down within 30 seconds whenFAN switch is placed in AUTO. position.2. Place SYSTEM switch in COOL position and FAN switchin AUTO. position. Set control below room temperature.Observe that compressor, outdoor fan, and indoor blowermotors start. Observe that cooling cycle shuts down whencontrol setting is satisfied.3. Place system switch in HEAT position. Set control aboveroom temperature. Observe that heating cycle shuts downwhen control setting is satisfied.4. When using an automatic changeover room thermostat,place both SYSTEM and FAN switches in AUTO. posi-tions. Observe that unit operates in Cooling mode whentemperature control is set to ‘‘call for Cooling’’ (belowroom temperature), and unit operates in Heating modewhen temperature control is set to ‘‘call for heating’’ (aboveroom temperature).IMPORTANT: Scroll compressors in the 048 and060 size units are direction-oriented. Three-phaseunits must be checked to ensure proper compressor3-phase power lead orientation. If not corrected within5 minutes, the internal protector will shut off thecompressor. The 3-phase power leads to the unit mustbe reversed to correct rotation. When turning back-wards, scroll compressors emit elevated noise lev-els, and the difference between compressor suctionand discharge pressures may be dramatically lowerthan normal.CHECKING AND ADJUSTING REFRIGERANT CHARGE— The refrigerant system is fully charged with R-22 refrig-erant, and is tested and factory sealed.NOTE: Adjustment of the refrigerant charge is not requiredunless the unit is suspected of not having the proper R-22charge. The charging label and the tables shown refer to sys-tem temperatures and pressures in Cooling mode only. If chargelevel is suspect in Heating mode, reclaim all refrigerant andcharge to nameplate amount.A superheat charging label is attached to the inside of thecompressor access door. The label includes a ‘‘Superheat Charg-ing Table’’ and a ‘‘Required Suction-Tube Temperature (F)’’chart.An accurate superheat, thermocouple-, or thermistor-typethermometer, a sling psychrometer, and a gage manifold arerequired when using the superheat charging method for evalu-ating the unit charge. Do not use mercury or small dial-typethermometers because they are not adequate for this type ofmeasurement.When evaluating the refrigerant charge, an indicated ad-justment to the specified factory charge must always bevery minimal. If a substantial adjustment is indicated,an abnormal condition exists somewhere in the coolingsystem, such as insufficient airflow across either coil orboth coils.Proceed as follows:1. Remove caps from low- and high-pressure servicefittings.2. Using hoses with valve core depressors, attach low- andhigh-pressure gage hoses to low- and high-pressure serv-ice fittings, respectively.3. Start unit in Cooling mode and let unit run until systempressures stabilize.4. Measure and record the following:a. Outdoor ambient-air temperature (F db).b. Indoor inlet-air temperature (F wb).c. Suction-tube temperature (F) at low-side servicefitting.d. Suction (low-side) pressure (psig).5. Using Superheat Charging Tables 4A-4G, compare outdoor-air temperature (F db) with indoor-air temperature (F wb)to determine desired system operating superheattemperature.6. Using Required Suction-Tube Temperature (F) Table 5,compare desired superheat temperature with suction (low-side) operating pressure (psig) to determine proper suction-tube temperature.7. Compare actual suction-tube temperature with propersuction-tube temperature. Using a tolerance of ±3° F, addrefrigerant if actual temperature is more than 3° F higherthan proper suction-tube temperature, or remove refrig-erant if actual temperature is more than 3° F lower thanrequired suction-tube temperature.NOTE: If the problem causing the inaccurate readings is arefrigerant leak, refer to Check for Refrigerant Leaks sec-tion on this page.18