Carrier GZ024 Installation Instructions Manual

Carrier GZ024 Installation Instructions Manual Manual pdf 31 page image

31TROUBLESHOOTING UNITS FOR PROPERSWITCHING BETWEEN LOW & HIGHSTAGESCheck the suction pressures at the service valves. Suction pressureshould be reduced by 3--10% when switching from low to highcapacity.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--2HI and PL5--5 C . When the compressor is operating in low stage,the 24V 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. Cy-cle the unloader on and off at 30 second plus intervals at theUser Interface (from low to high stage and back to lowstage). Wait 5 seconds after staging to high before taking areading. The compressor amperage should go up or downat least 20 percent.2. If the expected result is not achieved, remove the solenoidplug from the compressor and with the unit running and theUser Interface or thermostat calling for high stage, test thevoltage output at the plug with a DC voltmeter. The read-ing 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.Two Stage CompressorThe two stage compressor contains motor windings that provide2--pole (3500 RPM) operation.Compressor Internal ReliefThe compressor is protected by an internal pressure relief (IPR)which relieves discharge gas into the compressor shell whendifferential between suction and discharge pressure exceeds550--625 psi. The compressor is also protected by an internaloverload attached to motor windings.Compressor Control ContactorThe contactor has a 24volt coil. The electronic control boardcontrols the operation of the contactor.Troubleshoot CompressorIf the compressor fails to operate, Table 16 can be used to verify ifthere is any damage to the compressor windings causing systemmalfunction.Table 16 – Winding ResistanceCompressor OhmsModel Start Winding Run WindingGZ024 1.64 1.3GZ036 1.52 0.88GZ048 1.86 0.52GZ060 1.63 0.39GZ072 1.85 0.34Tolerance +/- 7%. All resistance values must be measured withcompressor at room temperature.Systems Communication FailureIf communication with the compressor control is lost with theCommunicating System Wall Control, the control will flash theappropriate fault code (see Table 15) to the rest of thecommunicating system, including the wall control and the indoorsplit geothermal unit.Model PlugEach control board contains a model plug. The model plug is usedto identify the type and size of unit to the control.The correct model plug must be installed for the system to operateproperly (see Table 17).Table 17 – Model Plug InformationModel Model PlugNumber Pins 1--- 4 Pins 2--- 3GZ024 HK70EZ001 5.1K 11KGZ036 HK70EZ002 5.1K 18KGZ048 HK70EZ003 5.1K 24KGZ060 HK70EZ004 5.1K 33KGZ072 HK70EZ005 5.1K 39KOn new units, the model and serial numbers are input into theboard’s memory at the factory. If a model plug is lost or missing atinitial installation, the unit will operate according to theinformation input at the factory and the appropriate error code willflash temporarily.NOTE: RCD replacement boards contain no model and serialinformation. If the factory control board fails, the model plug mustbe transferred from the original board to the replacement board forthe unit to operate.NOTE: The model plug takes priority over factory modelinformation input at the factory. If the model plug is removed afterinitial power up, the unit will operate according to the last validmodel plug installed, and flash the appropriate fault codetemporarily.Troubleshooting the Model PlugIf the unit is being identified incorrectly by model or size, verifythe plug resistance per Table 17. If resistance value verifies theplug is good, ensure the plug is dry and condensate free.NOTE: Dielectric grease (field supplied) can be used on modelplug pins if condensate has been noted after drying the plug.

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