Lennox HP29
Lennox HP29 Lennox HP29
PRESSURE SWITCHSAFETY CIRCUITCONNECTIONSNOTE − COMPONENT LOCATIONS WILL VARY WITH BOARD MANUFACTURERPRESSURE SWITCHSAFETY CIRCUITCONNECTIONSDIAGNOSTIC LEDsCONNECTION FORONE OPTIONALSWITCHHighPressureSwitchS4FACTORY−INSTALLEDJUMPER(Remove to addpressure switches)DIAGNOSTIC LEDsFACTORY−INSTALLEDJUMPER(Remove to addpressure switches)DEFROSTINTERVALTIMING PINSCONNECTIONS FORTWO OPTIONALSWITCHESAMBIENTTHERMISTORCONNECTIONOptionalswitchSERVICE LIGHTCONNECTIONS4HighPressureSwitchDEFROST INTERVALTIMING PINS24V TERMINAL STRIPCONNECTIONS24V TERMINAL STRIPCONNECTIONSFIGURE 6Defrost Control Timing PinsEach timing pin selection provides a differentaccumulated compressor run period during onethermostat run cycle. A defrost cycle is initiated at theend of this run period. The defrost interval can beadjusted to 30, 60 or 90 minutes. See figure 6. Thedefrost period is a maximum of 14 minutes and cannotbe adjusted. If no timing is selected, the control defaultsto 90 minutes.A TEST option is provided for troubleshooting. When thejumper is placed across the TEST pins, the timing of allfunctions is reduced by a factor of 128. For example, a 30minute interval during TEST is 14 seconds and the 14minute defrost is reduced to 6.5 seconds.The TEST mode may be started at any time. If the jumperis in the TEST position at power−up or for longer than fiveminutes, the control will ignore the TEST selection and willdefault to a 90 minute interval. In order to test defrostcycle, defrost thermostat must be closed or jumpered.Once defrost is initiated, remove jumper immediately.Failure to remove jumper will reduce defrost cycle toapproximately 3 seconds.Pressure Switch Safety CircuitThe defrost control incorporates a pressure switch safetycircuit that allows the application of up to two safety devices:high pressure and/or loss of charge. See figure 6. When thepressure switch opens, unit operation is suspended untilpressure switch closes. If the pressure switch opens for a thirdtime during one thermostat demand, the board will lockout untillow voltage is reset. This can be done by breaking 24 voltpower to terminal R" on the defrost control board.When only one pressure switch is used, wire the switch to thetwo outside terminals of the pressure switch connections.NOTE: If not using a pressure switch, the factory−installedjumper wire must be connected.Diagnostic LEDsThe defrost board uses two LEDs for diagnostics. The LEDsflash a specific sequence according to the condition.TABLE 4DEFROST CONTROL BOARD DIAGNOSTIC LEDMODE LED 1 LED 2Normal Operation/Power to boardFlash together withLED 2Pressure Switch Open Off OnBoard Malfunction On OnFlash together withLED 1Page 6
9 − Defrost SystemUnits built April 2002 and laterThe HP29 defrost system includes two components: adefrost thermostat and a defrost control.Defrost ThermostatThe defrost thermostat is located on the liquid line betweenthe check/expansion valve and the distributor. Whendefrost thermostat senses 42°F (5.5°C) or cooler, thethermostat contacts close and send a signal to the defrostcontrol board to start the defrost timing. It also terminatesdefrost when the liquid line warms up to 70°F (21°C).Defrost ControlThe defrost control board includes the combinedfunctions of a time/temperature defrost control, defrostrelay, diagnostic LEDs and terminal strip for field wiringconnections. See figure 7.The control provides automatic switching from normalheating operation to defrost mode and back. Duringcompressor cycle (call for defrost), the controlaccumulates compressor run times at 30, 60, or 90 minutefield−adjustable intervals. If the defrost thermostat is closedwhen the selected compressor run time interval ends, thedefrost relay is energized and defrost begins.Defrost Control Timing PinsEach timing pin selection provides a differentaccumulated compressor run time period during onethermostat run cycle. This time period must occur beforea defrost cycle is initiated. The defrost interval can beadjusted to 30 (T1), 60 (T2), or 90 (T3) minutes. Seefigure 7. The defrost timing jumper is factory−installed toprovide a 60−minute defrost interval. If the timing selectorjumper is not in place, the control defaults to a 90−minutedefrost interval.The maximum defrost period is 14minutes and cannot be adjusted.A TEST option is provided for troubleshooting. The TESTmode may be started any time the unit is in the heatingmode and the defrost thermostat is closed orjumpered. If the jumper is in the TEST position atpower-up, the control will ignore the test pins. When thejumper is placed across the TEST pins for two seconds, thecontrol will enter the defrost mode. If the jumper is removedbefore an additional 5−second period has elapsed (7seconds total), the unit will remain in defrost mode until thedefrost thermostat opens or 14 minutes have passed. If thejumper is not removed until after the additional 5−secondperiod has elapsed, the defrost will terminate and the testoption will not function again until the jumper is removedand re−applied.HP29 DEFROST CONTROL BOARDSTANDARD UNITSOPTIONAL UNITSHIGH PRESSURE SWITCHSAFETY CIRCUITCONNECTIONSNOTE − Remove factory−installed jumper to addpressure switch.CONNECTION FOROPTIONALHIGH PRESSURESWITCHCCYDEFROSTINTERVALTIMING PINSDIAGNOSTICLEDsPRESSURE SWITCHTERMINALS(Remove factory−installed jumperto installpressure switch.)DEFROSTINTERVALTIMINGPINSCCYDIAGNOSTICLEDsSERVICELIGHTTERMINALSAMBIENTTHERMISTERTERMINALS24VTERMINALSTRIPHighPressureSwitch24VTERMINALSTRIPS4FIGURE 7Page 7
- Page 1: Service LiteratureCorp. 9709−L5Re
- Page 5: 3 − Potential Relay K31 (Start)Al
- Page 9 and 10: B − Compressor (Reciprocating & S
- Page 11 and 12: IMPORTANTService valves are closed
- Page 13 and 14: IV − CHARGINGUnit charge is based
- Page 15 and 16: TABLE 13SUBCOOLING METHODAMBIENT TE
- Page 17 and 18: REFRIGERANT LINE SETS:HOW TO INSTAL
- Page 19 and 20: HP29 SINGLE-PHASE WITH RECIPROCATIN
- Page 21 and 22: HP29 SINGLE−PHASE WITH SCROLL COM
- Page 23 and 24: HP29 SINGLE−PHASE WITH SCROLLCOMP
- Page 25 and 26: HP29 THREE−PHASE WITH RECIPROCATI
- Page 27: HP29 THREE-PHASE OPERATING SEQUENCE
PRESSURE SWITCHSAFETY CIRCUITCONNECTIONSNOTE − COMPONENT LOCATIONS WILL VARY WITH BOARD MANUFACTURERPRESSURE SWITCHSAFETY CIRCUITCONNECTIONSDIAGNOSTIC LEDsCONNECTION FORONE OPTIONALSWITCHHighPressureSwitchS4FACTORY−INSTALLEDJUMPER(Remove to addpressure switches)DIAGNOSTIC LEDsFACTORY−INSTALLEDJUMPER(Remove to addpressure switches)DEFROSTINTERVALTIMING PINSCONNECTIONS FORTWO OPTIONALSWITCHESAMBIENTTHERMISTORCONNECTIONOptionalswitchSERVICE LIGHTCONNECTIONS4HighPressureSwitchDEFROST INTERVALTIMING PINS24V TERMINAL STRIPCONNECTIONS24V TERMINAL STRIPCONNECTIONSFIGURE 6Defrost Control Timing PinsEach timing pin selection provides a differentaccumulated compressor run period during onethermostat run cycle. A defrost cycle is initiated at theend of this run period. The defrost interval can beadjusted to 30, 60 or 90 minutes. See figure 6. Thedefrost period is a maximum of 14 minutes and cannotbe adjusted. If no timing is selected, the control defaultsto 90 minutes.A TEST option is provided for troubleshooting. When thejumper is placed across the TEST pins, the timing of allfunctions is reduced by a factor of 128. For example, a 30minute interval during TEST is 14 seconds and the 14minute defrost is reduced to 6.5 seconds.The TEST mode may be started at any time. If the jumperis in the TEST position at power−up or for longer than fiveminutes, the control will ignore the TEST selection and willdefault to a 90 minute interval. In order to test defrostcycle, defrost thermostat must be closed or jumpered.Once defrost is initiated, remove jumper immediately.Failure to remove jumper will reduce defrost cycle toapproximately 3 seconds.Pressure Switch Safety CircuitThe defrost control incorporates a pressure switch safetycircuit that allows the application of up to two safety devices:high pressure and/or loss of charge. See figure 6. When thepressure switch opens, unit operation is suspended untilpressure switch closes. If the pressure switch opens for a thirdtime during one thermostat demand, the board will lockout untillow voltage is reset. This can be done by breaking 24 voltpower to terminal R" on the defrost control board.When only one pressure switch is used, wire the switch to thetwo outside terminals of the pressure switch connections.NOTE: If not using a pressure switch, the factory−installedjumper wire must be connected.Diagnostic LEDsThe defrost board uses two LEDs for diagnostics. The LEDsflash a specific sequence according to the condition.TABLE 4DEFROST CONTROL BOARD DIAGNOSTIC LEDMODE LED 1 LED 2Normal Operation/Power to boardFlash together withLED 2Pressure Switch Open Off OnBoard Malfunction On OnFlash together withLED 1Page 6
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