Carrier 38AUZ*07 Series Installation, Start-up And Service Instructions Manual

Contents

19PRE-START-UPSystem Check1. Check all air handler(s) and other equipment auxiliarycomponents. Consult the manufacturer’s instructionsregarding any other equipment connected to the con-densing unit. If the unit has field-installed accessories,be sure all are properly installed and correctly wired. Ifused, the airflow switch must be properly installed.2. Be sure the unit is properly leak checked and dehydrated.3. Check tightness of all electrical connections.4. Open the liquid line and suction line service valves.5. Be sure the unit is properly charged. See “PreliminaryCharge”, below.6. The electrical power source must agree with the unit’snameplate rating.7. The crankcase heater must be firmly attached to the com-pressor crankcase. Be sure the crankcase is warm (heatermust be on for 24 hours before starting compressor).Turn On Crankcase HeaterTurn on the crankcase heater for 24 hours before starting theunit to be sure all the refrigerant is out of the oil. To energizethe crankcase heater, proceed as follows:1. Set the space thermostat set point above the space tem-perature so there is no demand for cooling.2. Close the field disconnect.Preliminary ChargeBefore starting the unit, charge liquid refrigerant into the highside of the system(s) through the liquid service valve(s). Theamount of refrigerant added must be at least 80% of theoperating charge listed in the Physical Data table (Tables 1Athrough 2B, pages 4 through 7). Open the liquid line andsuction line service valves. Allow high and low side pressuresto equalize before starting compressor. If pressures do notequalize readily, charge vapor on low side of system to assurecharge in the evaporator. Refer to GTAC II, Module 5,Charging, Recover, Recycling, and Reclamation for liquidcharging procedures.START-UP38AU UnitsThe compressor crankcase heater(s) must be on for 24 hoursbefore start-up. After the heater has been on for 24 hours, theunit can be started. If no time elapsed since the preliminarycharge step was completed, it is unnecessary to wait the 24-hour period.Preliminary Checks1. Check that electric power supply agrees with unitnameplate data.2. Verify that the compressor crankcase heater is securely inplace.3. Check that the compressor crankcase heater has been onat least 24 hours.4. Recheck for leaks using the procedure outlined in thePre-Start-Up section, Leak Test and Dehydration. If anyleaks are detected, repair as required. Evacuate anddehydrate as described in the Leak Test and Dehydrationsection.5. Ensure that the preliminary charge has been added asdescribed in the Pre-Start-Up section, PreliminaryCharge.6. All internal wiring connections must be tight, and allbarriers and covers must be in place.NOTE: The 38AU units are factory charged with therequired amount of oil. If recharging in required, useEmkarate RL 32-3MAF for the 38AU units.Compressor RotationOn 3-phase units with scroll compressors, it is important to becertain that the compressor is rotating in the proper direction.38AU units are equipped with a Comfort Alert DiagnosticModule (CADM). Alert Code 7 indicates reverse powerphasing.To correct phase order:1. Turn off power to the unit, tag disconnect.2. Reverse any two of the unit power leads.3. Reapply power to the compressor, verify correct pres-sures.To verify the compressor is rotating in the proper direction:1. Connect service gages to the suction and liquid pressurefittings.2. Energize the compressor.The suction pressure should drop and the liquid pressureshould rise, as is normal on any start-up.Compressor OverloadThis overload interrupts power to the compressor when eitherthe current or internal motor winding temperature becomes ex-cessive, and automatically resets when the internal temperaturedrops to a safe level. This overload may require up to 60 min-utes (or longer) to reset. If the internal overload is suspected ofbeing open, disconnect the electrical power to the unit andcheck the circuit through the overload with an ohmmeter orcontinuity tester.IMPORTANT: Before beginning Pre-Start-Up or Start-Up,review Start-Up Checklist at the back of this book. TheChecklist assures proper start-up of a unit and provides arecord of unit condition, application requirements, systeminformation, and operation at initial start-up.UNIT DAMAGE HAZARDDo not attempt to start the condensing unit, evenmomentarily, until the following steps have beencompleted. Compressor damage may result.UNIT DAMAGE HAZARDPrior to starting compressor, a preliminary charge ofrefrigerant must be added to avoid possible compressordamage.