Carrier Infinity 48XL Installation Instructions Manual

Also see for Infinity 48XL: Owner's information manual

Contents

Carrier Infinity 48XL Installation Instructions Manual Manual pdf 31 page image

- Defrost operation- Low ambient cooling- Crankcase heater operation- Compressor external protection- Pressure switch monitoring (refrigerant)- Time delaysFURNACE BOARDThe furnace board controls the following functions:- Indoor blower operation- Gas valve- Inducer motor- Remote sparker module- Pressure switch monitoring (gas)SYSTEMS COMMUNICATION FAILUREIf communication with the Infinity Control is lost with the UI, thecontrols will flash the appropriate fault codes. Check the wiring tothe UI, indoor and outdoor units.MODEL PLUGThe HP/AC control board must have a valid model plug to operate.If a valid model plug is not detected, it will not operate and thecontrol will flash the appropriate fault code, shown in Table 5.PRESSURE SWITCH PROTECTION-REFRIGERANTThe unit is equipped with high- and low-pressure switches. If thecontrol senses the opening of a high- or low-pressure switch, itwill respond as follows:1. De-energize the compressor contactor (HPS1 & LPS) or thecompressor solenoid contactor (HPS2).2. Keep the outdoor fan operating for 15 minutes.3. Display the appropriate fault codes.4. After a 15 minute delay, if there is still a call for cooling andthe LPS or HPS is reset, the compressor contactor isenergized.5. If LPS or HPS has not closed after a 15 minute delay, theoutdoor fan is turned off. If the open switch closes anytimeafter the 15-minute delay, then resume operation with a callfor cooling.6. If LPS or HPS trips 3 consecutive cycles, the unit operationis locked out for 4 hours.7. In the event of a high-pressure switch trip or high pressurelockout, check the refrigerant charge, outdoor fan operationand outdoor coil for airflow restrictions.8. In the event of a low-pressure switch trip or low pressurelockout, check the refrigerant charge and indoor airflow.CONTROL FAULTIf the HP/AC control board has failed, the control will flash theappropriate fault code (See TaMe 5). The control board should bereplaced.BROWN OUT PROTECTIONIf the line voltage is less than 187v for at least 4 seconds, theappropriate compressor contactor and fan relay are de-energized.Compressor and fan operation are not allowed until voltage is aminimum of 190v. The control will flash the appropriate faultcode (See Table 5).230V LINE (POWER DISCONNECT) DETECTIONIf there is no 230v at the compressor contactor when the unit ispowered and cooling demand exists, the appropriate error code isdisplayed. Verify that the disconnect is closed and 230v wiring isconnected to the unit.COMPRESSOR VOLTAGE SENSINGThe control board input terminals VS and L2 (See Fig. 18) areused to detect compressor voltage status, and alert the user ofpotential problems. The control continuously monitors the highvoltage on the run capacitor of the compressor motor. Voltageshould be present any time the compressor contactor is energized,and voltage should not be present when the contactor isde-energized.CONTACTOR SHORTED DETECTIONIf there is compressor voltage sensed when there is no demand forcompressor operation, the contactor may be stuck closed or there isa wiring error. The control will flash the appropriate fault code.COMPRESSOR THERMAL CUTOUTIf the control senses the compressor voltage after start-up, and isthen absent for 10 consecutive seconds while cooling demandexists, the thermal protector is open. The control de-energizes thecompressor contactor for 15 minutes, but continues to operate theoutdoor fan. The control Status LED will flash the appropriatecode shown in Table 5. After 15 minutes, with a call for low orhigh stage cooling, the compressor contactor is energized. If thethermal protector has not re-set, the outdoor fan is turned off. Ifthe call for cooling continues, the control will energize thecompressor contactor every 15 minutes. If the thermal protectorcloses (at the next 15 minute interval), check the unit will resumeoperation.If the thermal cutout trips for three consecutive cycles, then unitoperation is locked out for 4 hours and the appropriate fault code isdisplayed.NO 230V AT COMPRESSORIf the compressor voltage is not sensed when the compressorshould be starting, the contactor may be stuck open or there is awiring error. The control will flash the appropriate fault code.Check the contactor and control box wiring.TROUBLESHOOTING UNIT FOR PROPER SWITCHINGBETWEEN LOW & HIGH STAGESCheck the suction pressures at the service valves. Suction pressureshould be reduced by 3-10% when switching from low to highcapacity.NOTE: The liquid pressures are very similar between low andhigh stage operation, so liquid pressure should not be used fortroubleshooting.Compressor current should increase 20-45% when switching fromlow to high stage. The compressor solenoid, when energized inhigh stage, should measure 24vac.COMPRESSOR INTERNAL RELIEFThe compressor is protected by an internal pressure relief (IPR)which relieves discharge gas into compressor shell whendifferential between suction and discharge pressures exceeds 550 -625 psi. The compressor is also protected by an internal overloadattached to motor windings.TEMPERATURE THERMISTORSThermistors are electronic devices which sense temperature. As thetemperature increases, the resistance decreases. Thermistors areused to sense outdoor ambient (OAT) and coil temperature (OCT).Refer to Fig. 25 for resistance values versus temperature. See Fig.26 for OCT location.If the outdoor ambient or coil thermistor should fail, the HP/ACcontrol will flash the appropriate fault code (See Table 5).IMPORTANT: Coil thermistor is factory mounted. Check toinsure thermistor is mounted properly. Outdoor air thermistor(OAT) is field mounted and connected. Verify that the OAT hasbeen properly installed.31