Carrier Infinity 24ANB7 Installation Instructions Manual

Also see for 24ANB1 Infinity: Product data Wiring diagram

Contents

10Compressor Voltage SensingThe control board input terminals labeled VS and L2 (see Fig. 7)are used 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 appropriate code shown inTable 6. After 15 minutes, with a call for low or high stage cooling,the compressor contactor is energized. If the thermal protector hasnot reset, the outdoor fan is turned off. If the call for coolingcontinues, the control will energize the compressor contactor every15 minutes. If the thermal protector closes, (at the next 15 minuteinterval check), the unit will resume operation. If the thermalcutout trips for three consecutive cycles, then unit operation islocked out for 4 hours and the appropriate fault code is displayed.No 230V at CompressorIf the compressor voltage is not sensed when the compressorshould be starting, the appropriate contactor may be stuck open orthere is a wiring error. The control will flash the appropriate faultcode. Check the contactor and control box wiring.Troubleshooting units 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 to 45% when switchingfrom low to high stage. The compressor solenoid when energizedin high stage, should measure 24vac across pin numbers PL5--2 HIand PL5--5 C . When the compressor is operating in low stage, the24v DC compressor solenoid coil is de--energized. When thecompressor is operating in high stage, the 24v DC solenoid coil isenergized.The solenoid plug harness that is connected to the compressor hasan internal rectifier that converts the 24v AC signal to 24v DC.DO NOT INSTALL A PLUG WITHOUT AN INTERNALRECTIFIER.Unloader Test ProcedureThe unloader is the compressor internal mechanism, controlled bythe DC solenoid, that modulates between high and low stage. If itis suspected that the unloader is not working, the followingmethods may be used to verify operation.1. Operate the system and measure compressor amperage.Cycle the unloader on and off at 30 second plus intervals atthe UI (from low to high stage and back to low stage). Wait5 seconds after staging to high before taking a reading. Thecompressor amperage should go up or down at least 20 per-cent.2. If step one does not give the expected results, remove thesolenoid plug from the compressor and, with the unit run-ning and the UI (or Thermostat) calling for high stage, testthe voltage output at the plug with a DC voltmeter. Thereading should be 24 volts DC.3. If the correct DC voltage is at the control circuit moldedplug, measure the compressor unloader coil resistance. Theresistance should be approximately 330 or 1640 ohms de-pending on unloader coil supplier. If the coil resistance isinfinite or is grounded, the compressor must be replaced.MAJOR COMPONENTS2--Stage ControlThe 2--stage control board controls the following functions:— Compressor high and low stage operation— Outdoor fan motor operation— Low ambient cooling— Compressor external protection— Pressure switch monitoring— Time delaysField ConnectionsOn models with non--communicating (non--Infinity) system, the2--stage control receives 24vac low--voltage control system inputsthrough the C, Y1, and Y2 connections located at the bottom of thecontrol board (see Fig. 7). The OD units can be controlled using astandard 2--stage thermostat or Infinity User Interface.2--Stage CompressorThe 2--stage compressor contains motor windings that provide2--pole (3500 RPM) operation. Refer to Table 4 for correctwinding resistance.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 psig The compressor is also protected by an internal overloadattached to motor windings.Compressor Control ContactorThe contactor has a 24 volt coil. The electronic control boardcontrols the operation of the appropriate contactor.24ANB7 / 24ANB1