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Carrier 48GC04 - User Manual

Carrier 48GC04
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Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.
Catalog No. 04-53480212-01 Printed in U.S.A. Form 48GC-4-6-01SM Rev. A Pg 1 8-19 Replaces: New
Service and Maintenance Instructions
SAFETY CONSIDERATIONS . . . . . . . . . . . . . . . . . . . 2
UNIT ARRANGEMENT AND ACCESS . . . . . . . . . . . . 3
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Routine Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . 3
Filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
SUPPLY FAN (BLOWER) SECTION . . . . . . . . . . . . . . 4
Supply Fan (Direct-Drive) . . . . . . . . . . . . . . . . . . . . . . 4
Staged Air Volume . . . . . . . . . . . . . . . . . . . . . . . . . . 11
COOLING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Condenser Coil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Condenser Coil Maintenance and Cleaning
Recommendation . . . . . . . . . . . . . . . . . . . . . . . . . 11
Evaporator Coil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
THERMOSTATIC EXPANSION VALVE (TXV) . . . . . 13
TXV Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Replacing TXV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Refrigerant System Pressure Access Ports . . . . . . 14
PURON (R-410A) REFRIGERANT . . . . . . . . . . . . . . 15
Refrigerant Charge . . . . . . . . . . . . . . . . . . . . . . . . . . 15
COOLING CHARGING CHARTS . . . . . . . . . . . . . . . . 15
COMPRESSOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Lubrication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Replacing Compressor . . . . . . . . . . . . . . . . . . . . . . . 17
Compressor Rotation . . . . . . . . . . . . . . . . . . . . . . . . 17
Filter Drier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Condenser-Fan Adjustment . . . . . . . . . . . . . . . . . . . 17
Troubleshooting Cooling System . . . . . . . . . . . . . . 19
CONVENIENCE OUTLETS . . . . . . . . . . . . . . . . . . . . 20
Convenience Outlets . . . . . . . . . . . . . . . . . . . . . . . . 20
Installing Weatherproof Cover . . . . . . . . . . . . . . . . . 20
Non-Powered Type . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Unit-Powered Type . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Duty Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Fuse on Powered Type . . . . . . . . . . . . . . . . . . . . . . . 21
SMOKE DETECTORS . . . . . . . . . . . . . . . . . . . . . . . . 21
System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Smoke Detector Sensor . . . . . . . . . . . . . . . . . . . . . . 21
Smoke Detector Locations . . . . . . . . . . . . . . . . . . . . 22
Completing Installation of Return Air Smoke
Detector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
FIOP Smoke Detector Wiring and Response . . . . . 23
SENSOR AND CONTROLLER TESTS . . . . . . . . . . . 24
Sensor Alarm Test . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Controller Alarm Test . . . . . . . . . . . . . . . . . . . . . . . . 24
Dirty Controller Test . . . . . . . . . . . . . . . . . . . . . . . . . 24
Dirty Sensor Test . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Changing the Dirt Sensor Test . . . . . . . . . . . . . . . . 25
Remote Station Test . . . . . . . . . . . . . . . . . . . . . . . . .25
SD-TRK4 Remote Alarm Test Procedure . . . . . . . . .25
Remote Test/Reset Station Dirty Sensor Test . . . . .25
Dirty Sensor Test Using an SD-TRK4 . . . . . . . . . . .25
Detector Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . .25
Indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
PROTECTIVE DEVICES . . . . . . . . . . . . . . . . . . . . . . .27
Compressor Protection . . . . . . . . . . . . . . . . . . . . . . .27
Relief Device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27
Control Circuit, 24-V . . . . . . . . . . . . . . . . . . . . . . . . .27
GAS HEATING SYSTEM . . . . . . . . . . . . . . . . . . . . . .27
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27
Fuel Types and Pressures . . . . . . . . . . . . . . . . . . . .28
Flue Gas Passageways . . . . . . . . . . . . . . . . . . . . . . .28
Combustion-Air Blower . . . . . . . . . . . . . . . . . . . . . . .28
Burners and Igniters . . . . . . . . . . . . . . . . . . . . . . . . .29
Burner Ignition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32
Orifice Replacement . . . . . . . . . . . . . . . . . . . . . . . . .32
Troubleshooting Heating System . . . . . . . . . . . . . . .34
SYSTEMVU CONTROL SYSTEM . . . . . . . . . . . . . . . .36
SystemVu Interface . . . . . . . . . . . . . . . . . . . . . . . . . .36
Additional SystemVu Installation and
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . .36
RTU OPEN CONTROL SYSTEM . . . . . . . . . . . . . . . .37
Sensory/Accessory Installation . . . . . . . . . . . . . . . .37
Additional RTU Open Installation and
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . .38
ECONOMIZER SYSTEMS . . . . . . . . . . . . . . . . . . . . .38
EconoMi$er2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39
EconoMi$er IV (Field-Installed Accessory) . . . . . . .40
Economi$er X (Factory Option) . . . . . . . . . . . . . . . .47
PRE-START-UP/START-UP . . . . . . . . . . . . . . . . . . . .60
START-UP, GENERAL . . . . . . . . . . . . . . . . . . . . . . . .60
Unit Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . .60
Additional Installation/Inspection . . . . . . . . . . . . . .60
Gas Piping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .60
Return-Air Filters . . . . . . . . . . . . . . . . . . . . . . . . . . . .61
Outdoor-Air Inlet Screens . . . . . . . . . . . . . . . . . . . . .61
Compressor Mounting . . . . . . . . . . . . . . . . . . . . . . . .61
Internal Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61
Refrigerant Service Ports . . . . . . . . . . . . . . . . . . . . .61
Compressor Rotation . . . . . . . . . . . . . . . . . . . . . . . .61
Cooling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61
Main Burner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61
Heating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61
Ventilation (Continuous Fan) . . . . . . . . . . . . . . . . . .62
FASTENER TORQUE VALUES . . . . . . . . . . . . . . . . .62
START-UP, RTU OPEN CONTROLS . . . . . . . . . . . . .62
START-UP, SYSTEMVU CONTROLS . . . . . . . . . . . .62
48GC04-06
Single Package Rooftop Gas Heat/Electric Cooling Unit
with Puron
®
(R-410A) Refrigerant
3 to 5 Nominal Tons

Table of Contents

Questions and Answers

  • T
    Theresa AndersonAug 18, 2025
    Why does my Carrier 48GC04 compressor operate continuously?
    • H
      Heather ReedAug 18, 2025
      If your Carrier Air Conditioner compressor is operating continuously, several factors could be responsible. A dirty air filter can cause this issue; replace the filter. The unit might be undersized for the load, necessitating a reduction in load or an increase in unit size. Ensure the thermostat isn't set too low in cooling mode by resetting it. A low refrigerant charge is another possibility; locate the leak, repair it, and recharge the system. Air in the system can also cause continuous operation; recover the refrigerant, evacuate the system, and recharge it. Lastly, check for a dirty or restricted outdoor coil and clean the coil or remove any restrictions.
  • L
    Lauren BennettAug 21, 2025
    What causes excessive head pressure in Carrier 48GC04 Air Conditioner?
    • J
      jasonjohnsonAug 21, 2025
      Excessive head pressure in your Carrier Air Conditioner can be caused by several factors. A dirty air filter requires replacement. A dirty outdoor coil needs cleaning. If the system is overcharged with refrigerant, the excess refrigerant must be recovered. Air in the system necessitates recovering the refrigerant, evacuating the system, and recharging. Lastly, check if the condensing air is restricted or short-cycling and determine the cause to correct it.
  • M
    moralessaraAug 25, 2025
    What to do if Carrier Air Conditioner compressor will not start but outdoor fan runs?
    • W
      Walter GuerreroAug 26, 2025
      If the compressor in your Carrier Air Conditioner will not start but the outdoor fan runs, there might be faulty wiring or loose connections in the compressor circuit; check the wiring and repair or replace as needed. The compressor motor may be burned out, seized, or have an internal overload open; determine the cause and replace the compressor, or allow enough time for the internal overload to cool and reset. A defective run/start capacitor, overload, or start relay could also be the issue; determine the cause and replace the component, or allow enough time for the internal overload to cool and reset. Lastly, one leg of 3-phase power might be dead; replace the fuse or reset the circuit breaker and determine the cause.
  • D
    dshermanAug 28, 2025
    What causes low head pressure in Carrier 48GC04 Air Conditioner?
    • G
      Gerald KimAug 28, 2025
      Low head pressure in a Carrier Air Conditioner can stem from several issues. A low refrigerant charge requires checking for leaks, repairing them, and recharging the system. Defective compressor scroll plates necessitate compressor replacement. A restriction in the liquid tube requires removing the restriction.
  • T
    teresa58Sep 3, 2025
    What causes excessive suction pressure in Carrier 48GC04?
    • M
      Marissa WareSep 3, 2025
      Excessive suction pressure in your Carrier Air Conditioner may be attributed to a high heat load, requiring a check for the source and its elimination. Defective compressor scroll plates necessitate replacing the compressor. Refrigerant overcharge requires the recovery of excess refrigerant.
  • P
    Paula FloresSep 10, 2025
    How to fix a Carrier 48GC04 Air Conditioner compressor that makes excessive noise?
    • E
      Eric EverettSep 10, 2025
      If your Carrier Air Conditioner compressor is making excessive noise, it might be rotating in the wrong direction. To fix this, reverse the 3-phase power leads as described in the Start-Up section.
  • J
    joshuahigginsNov 13, 2025
    What to do if compressor and outdoor fan will not start on my Carrier 48GC04 Air Conditioner?
    • M
      matthewcunninghamNov 13, 2025
      If the compressor and outdoor fan of your Carrier Air Conditioner won't start, it could be due to a power failure. In this case, you should call the power company. Other potential causes include a blown fuse or tripped circuit breaker, which requires replacing the fuse or resetting the breaker after determining the root cause. It may also be due to a defective thermostat, contactor, transformer, control relay, or capacitor, all of which require component replacement. Insufficient line voltage or incorrect wiring can also be the cause, requiring you to determine and correct the voltage issue or check the wiring diagram and rewire correctly. Make sure that the thermostat setting is not too high, and lower it below room temperature. Also, the high or low pressure switch, or freeze-up protecti...
  • C
    cynthia18Dec 1, 2025
    Why does my Carrier 48GC04 compressor cycle too often?
    • T
      Thomas CaldwellDec 1, 2025
      If the compressor in your Carrier Air Conditioner cycles more frequently than normal, it could be due to several reasons. The system might be overcharged or undercharged with refrigerant, requiring you to recover the refrigerant, evacuate the system, and recharge it to the nameplate specifications. A defective compressor may also cause this issue, necessitating replacement and identification of the root cause. Insufficient line voltage can also be a factor; determine the cause and correct it. A blocked outdoor coil or a dirty air filter can also lead to cycling; determine the cause and correct it. Other potential causes include a defective run/start capacitor, overload, or start relay, a defective thermostat, or a faulty outdoor-fan (cooling) or indoor-fan (heating) motor or capacitor; det...

Carrier 48GC04 Specifications

General IconGeneral
EER11.0
SEER14.0
RefrigerantR-410A
Voltage208/230V
Phase1
Compressor TypeScroll
TypeAir Conditioner

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