Carrier 48PG20 - Page 68

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Fig. 14 — Low Voltage Control Schematic — 48PG20-28 Units without Humidi-MiZer™ System

a48-7627

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Table of Contents1
Safety Considerations2
General2
Basic Control Usage2
Comfortlink Control2
Scrolling Marquee3
Accessory Navigator™ Display3
Operation3
System Pilot4
CCN Tables and Display4
Conventions Used in this Manual4
Start-Up6
Unit Preparation6
Compressor Mounting6
Refrigerant Service Ports6
Crankcase Heater(S)6
Compressor Rotation6
Internal Wiring6
Subcooler Heat Exchanger (SHX)6
Evaporator Fan6
Condenser Fans and Motors6
Orifice Change (48PG Only)7
Power Supply7
Air Baffles7
Accessory Installation7
Controls Quick Start35
Thermostat Control35
Space Temperature Sensor Control - Direct Wired (T-55 or T-56)35
Space Temperature Sensor Control - CCN (T-58)35
Space Temperature Sensor Control - CCN Linkage35
Space Humidity Control - Humidistat35
Space Humidity Control - Thermidistat35
Space Humidity Control - Relative Humidity Sensor35
CCN Communication35
Accessories35
Control Configuration Checklist36
Programming Operating Schedules36
Service Test36
Third Party Control38
Thermostat38
Humidistat38
Humidity Sensor38
Remote Occupancy38
Fire Shutdown38
Alarm Output38
Outdoor Enthalpy38
IAQ Switch39
IAQ Sensor39
OAQ Sensor39
Controls Operation39
Display Configuration39
Modes39
Unit Configuration39
Occupancy Determination40
Indoor Fan41
Cooling41
Thermostat Control41
Gas Heating (48PG Units)42
- Space Sensor Control43
Electric Heat (50PG Units)44
Economizer44
- Economizer Actuator Communications45
Optional Humdi-Mizer Dehumidification System45
Indoor Air Quality49
Temperature Compensated Start51
Carrier Comfort Network® (CCN) Configuration51
Alarm Handling52
Troubleshooting52
Complete Unit Stoppage52
Restart Procedure54
Control Module Communication54
Alarms and Alerts54
- Viewing and Clearing Unit Alarms54
- Diagnostic Alarm Codes and Possible Causes54
Cooling Troubleshooting57
Humidi-Mizer Troubleshooting57
Economizer Troubleshooting57
Heating Troubleshooting60
Phase Loss Protection60
Thermistor Troubleshooting61
Transducer Troubleshooting64
Forcing Inputs and Outputs64
Major System Components67
General67
Main Base Board (MBB)67
Economizer Control Board (ECB)67
Integrated Gas Control (IGC) Board67
Low Voltage Terminal Strip (TB2)67
Scrolling Marquee Display80
Accessory Navigator™ Display80
Carrier Comfort Network® Interface80
Subcooler Heat Exchanger80
Return/Supply Air Temperature Sensor82
Field-Installed Accessories82
- Space Temperature Sensor (T-55)82
- Space Temperature Sensor (T-56)82
- Space Temperature Sensor (T-58)82
- Space Temperature Sensor Averaging82
Service85
Cleaning85
Lubrication86
Manual Outdoor Air Damper87
Economizer Adjustment87
Evaporator Fan Service and Replacement87
Evaporator Fan Performance Adjustment87
Evaporator Fan Belt Tension Adjustment88
Condenser-Fan Adjustment88
Verify Sensor Performance88
Economizer Operation During Power Failure88
Evacuation88
Refrigerant Charge89
Gas Valve Adjustment (48PG Only)90
High Altitude (48PG Only)90
Main Burners (48PG Only)91
Control Circuit 24-V92
Filter Drier92
Protective Devices92
Relief Devices92
Replacement Parts92
Diagnostic Leds92
Appendix A - Local Display and Ccn Tables93
Appendix B - Control Modes with Humidi-Mizer System and Economizer104
Configuration Log108
Unit Start-Up Checklist112

Carrier 48PG20 - Page 68

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