Carrier 50JZ024 Installation, Start-up And Service Instructions Manual

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Contents

Exposure, even if immediately cleaned up, may cause embrittle-ment (leading to cracking) to occur in one year or more. Whenperforming any service that may risk exposure of compressor oil tothe roof, take appropriate precautions to protect roofing. Proce-dures which risk oil leakage include, but are not limited to,compressor replacement, repairing refrigerant leaks, replacingrefrigerant components such as filter drier, pressure switch, me-tering device, coil, accumulator, or reversing valve.SYNTHETIC ROOF PRECAUTIONARY PROCEDURE1. Cover extended roof working area with an impermeablepolyethylene (plastic) drip cloth or tarp. Cover an approximate10 x 10 ft. area.2. Cover area in front of the unit service panel with a terry clothshop towel to absorb lubricant spills and prevent run-offs, andprotect drop cloth from tears caused by tools or components.3. Place terry cloth shop towel inside unit immediately undercomponent(s) to be serviced and prevent lubricant run-offsthrough the louvered openings in the base pan.4. Perform required service.5. Remove and dispose of any oil contaminated material perlocal codes.LIQUID LINE FILTER DRIER — The biflow filter drier isspecifically designed to operate with Puron. Use only factory-authorized components. Filter drier must be replaced whenever therefrigerant system is opened. When removing a filter drier, use atubing cutter to cut the drier from the system. Do not unsweat afilter drier from the system. Heat from unsweating will releasemoisture and contaminants from drier into system.PURON (R-410A) REFRIGERANT CHARGING — Refer to unitinformation plate and charging chart. Some R-410A refrigerantcylinders contain a dip tube to allow liquid refrigerant to flowfrom cylinder in upright position. For cylinders equipped with adip tube, charge Puron units with cylinder in upright position anda commercial metering device in manifold hose. Charge refrigerantinto suction-line.SYSTEM INFORMATIONTIME-DELAY RELAY — The Time-Delay Relay (TDR) is asolid-state control, recycle delay timer which keeps indoor bloweroperating for 60 sec on 030-060 sizes or 30 sec on 024 size afterthermostat is satisfied. This delay enables blower to removeresidual cooling in coil after compression shutdown, therebyimproving efficiency of system. The sequence of operation is thaton closure of wall thermostat and at end of a fixed on delay of 1sec, fan relay is energized. When thermostat is satisfied, an offdelay is initiated. When fixed delay of 60 ± 5 sec or 30 ± 5 iscompleted, fan relay is de-energized and fan motor stops. If wallthermostat closes during this delay, TDR is reset and fan relayremains energized. TDR is a 24v device that operates within arange of 15v to 30v and draws about 0.5 amps. If the blower runscontinuously instead of cycling off when the fan switch is set onAUTO, the TDR is probably defective and must be replaced.LOSS OF CHARGE SWITCH — The loss of charge switch is aprotective device wired into control circuit (low voltage). It shutsoff the compressor if abnormally low pressures are present in therefrigeration circuit.NOTE: Because these switches are attached to refrigerationsystem under pressure, it is not advisable to remove this device fortroubleshooting unless you are reasonably certain that a problemexists. If switch must be removed, remove and recover all systemcharge so that pressure gauges read 0 psi. Never open systemwithout breaking vacuum with dry nitrogen.CHECK DEFROST THERMOSTAT — There is a liquid headerwith a brass distributor and feeder tube going into outdoor coil. Atthe end of 1 of the feeder tubes, there is a 3/8-in. OD stub tubeapproximately 3 in. long (See Fig. 31). The defrost thermostatshould be located on stub tube. Note that there is only 1 stub tubeused with liquid header, and on most units it is the bottom circuit.DEFROST THERMOSTATS — Defrost thermostat signals heatpump that conditions are right for defrost or that conditions havechanged to terminate defrost. It is a thermally actuated switchclamped to outdoor coil to sense its temperature. Normal tempera-ture range is closed at 30˚ +/- 3˚F and open at 80˚ +/- 5˚F.NOTE: The defrost thermostat must be located on the liquid sideof the outdoor coil on the bottom circuit and as close to the coil aspossible.Fig. 31—Defrost ThermostatC99029FEEDER TUBESTUB TUBEDEFROSTTHERMOSTAT22