Carrier 48EZ-A Troubleshooting Guide Cooling or Heat Pump Heating Mode, Symptom Cause Remedy

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Table 11 – Troubleshooting Guide - Cooling or Heat Pump Heating Mode

 

 

 

SYMPTOM

CAUSE

REMEDY

 

Power Failure

Call power company.

 

Fuse blown or circuit breaker tripped

Replace fuse or reset circuit breaker.

Compressor and Outdoor fan will not

Defective thermostat, contactor, transformer, or control

Replace component.

relay

start.

 

Insufficient line voltage

Determine cause and correct.

 

 

Incorrect or faulty wiring

Check wiring diagram and rewire correctly.

 

Thermostat setting too high

Lower thermostat setting below room temperature.

 

Faulty wiring or loose connections in compressor circuit

Check wiring and repair or replace.

 

Compressor motor burned out, seized, or internal over-

Determine cause Replace compressor.

Compressor will not start but Outdoor

load open

 

fan runs.

 

 

Defective run/start capacitor, overload, start relay

Determine cause and replace.

 

One leg of 3---phase power dead

Replace fuse or reset circuit breaker. Determine

 

cause.

 

 

Three ---phase scroll compressor makes

Scroll compressor is rotating in the wrong direction

Correct the direction of rotation by reversing the

excessive noise, and there may

3---phase power leads to the unit.

be a low pressure differential.

 

 

 

 

Refrigerant overcharge or undercharge

Recover refrigerant, evacuate system, and recharge

 

to capacities shown on nameplate.

 

 

 

Defective compressor

Replace and determine cause.

Compressor cycles (other than normally

Insufficient line voltage

Determine cause and correct.

Blocked Outdoor

Determine cause and correct.

satisfying thermostat).

 

 

Defective run/start capacitor, overload or start relay

Determine cause and replace.

 

Defective thermostat

Replace thermostat.

 

Faulty Outdoor ---fan motor or capacitor

Replace.

 

Damaged reversing valve

Determine cause and correct

 

Restriction in refrigerant system

Locate restriction and remove.

 

Dirty air filter

Replace filter.

 

Unit undersized for load

Decrease load or increase unit size.

 

Thermostat set too low

Reset thermostat.

 

Low refrigerant charge

Locate leak, repair, and recharge.

Compressor operates continuously.

Mechanical damage in compressor.

Replace compressor.

Air in system

Recover refrigerant, evacuate system, and recharge.

 

 

 

Check defrost time settings, Reset as necessary

 

Frosted coil with incorrect defrost operation

Check defrost temperature switch, Replace as nec-

 

 

essary

 

Outdoor coil dirty or restricted

Clean coil or remove restriction .

 

Dirty air filter

Replace filter.

Excessive head pressure.

Dirty Indoor or Outdoor coil

Clean coil.

Refrigerant overcharged

Recover excess refrigerant.

 

Air in system

Recover refrigerant, evacuate system, and recharge.

 

Indoor or Outdoor air restricted or air short---cycling

Determine cause and correct.

Head pressure too low.

Low refrigerant charge

Check for leaks, repair, and recharge.

Compressor IPR leaking

Replace compressor.

 

Restriction in liquid tube

Remove restriction.

 

High heat load

Check for source and eliminate.

Excessive suction pressure.

Compressor IPR leaking

Replace compressor.

Refrigerant overcharged

Recover excess refrigerant.

 

 

Reversing valve hung up or leaking internally

Replace valve

 

Dirty air filter

Replace Filter.

 

Low refrigerant charge

Check for leaks, repair, and recharge.

 

Metering device or low side restricted

Remove source of restriction.

 

Insufficient Indoor airflow

Increase air quantity. Check filter — replace if neces-

Suction pressure too low.

sary.

 

Temperature too low in conditioned area

Reset thermostat.

 

 

Outdoor ambient below 55°F (12.8°C)

Install low---ambient kit.

 

Field---installed filter ---drier restricted

Replace.

 

(Heat) Outdoor coil frosted

Move timer on control board to 30 minutes between

 

defrost cycles

 

 

Compressor runs but outdoor fan does

NC (normally closed) contacts on defrost board open

Check condition of relay on board Replace if neces-

not

sary

 

48EZ -- A

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Contents Safety Considerations Table of ContentsProvide Unit Support Receiving and InstallationIntroduction Check Equipment48EZ-A24-36 Unit Dimensions 48EZ-A42-60 Unit Dimensions Small Curb Hazard Rig and Place UnitProvide Clearances Personal Injury or Property DamageInspection Install Flue HoodInstall Gas Piping Connect Condensate DrainSediment Trap Fire or Explosion HazardUnit Size 48EZ Physical Data Unit 48EZ-AHeating Inputs Physical Data Unit 48EZ-A Cont’dMaximum Gas Flow Capacity Unit Component Damage Hazard Install Duct ConnectionsConfiguring Units for Downflow Vertical Discharge Alternate MethodSupply Duct Panels Control Voltage Connections Install Electrical ConnectionsSpecial Procedures for 208-V Operation High-Voltage ConnectionsFIRE, EXPLOSION, Electrical Shock Hazard Balance Point Setting-Thermidistat or Hybrid ThermostatPRE-START-UP Transformer ProtectionUnit Sequence of Operation Start-up Heating and Make Adjust- mentsSTART-UP Check for Refrigerant LeaksUnit Damage Hazard Adjust Gas InputCheck Heating Control Check Gas InputCheck Burner Flame Airflow and Temperature RiseLimit Switches Rollout SwitchChecking Cooling Control Operation Start-up Cooling and Make Adjust- mentsChecking and Adjusting Refrigerant Charge Indoor Airflow and Airflow AdjustmentsColor Coding for Indoor Fan Motor Leads Two Cooling Fan Speeds Set-up Dehumidification feature usedGas Heating Fan Speed Set-up Continuous Fan Operation48EZ-A Wet Coil Pressure Drop IN. W.C Filter Pressure Drop Table IN. W.C741 638 547 415 Heating Low Blue 1234 1168 1093 1021 961 894 825 759 687 Heating Low Blue 1736 1695 1642 1601 1553 1512 1465 1427 1381 65oF Heating 1927 1893 1858 1824 1791 1759 1720 1689 1640 65oF Heating 48EZ a 208/230-3-60 Wiring Diagram, Unit 48EZ-A Cooling Charging Table-Subcooling Indoor Blower and Motor MaintenanceCleaning the Blower Motor and Wheel Air FilterMain Burners Limit SwitchInduced Draft combustion air Blower Assembly Burner IgnitionRefrigerant Circuit Electrical Controls and WiringOutdoor Fan Indoor Airflow Pressure SwitchesLoss of Charge Switch Gas InputExplosion Hazard High-Pressure SwitchCopeland Scroll Compressor Puron Refrigerant Compressor Oil Unit Operation and Safety HazardRefrigerant System Puronr R-410A Quick Reference Guide TroubleshootingSTART-UP Checklist Symptom Cause Remedy Troubleshooting Guide Cooling or Heat Pump Heating ModeTroubleshooting Guide-LED Error Codes Troubleshooting Guide-HeatingIII. START-UP Electrical Supply Voltage Compressor Amps TemperaturesRemove and Store in Job Files Preliminary Information Model noCatalog No 48EZ---06SI
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48EZ-A specifications

The Carrier 48EZ-A and 48VT-A are two advanced rooftop unit air conditioners that exemplify innovation and efficiency in HVAC technology. Designed for commercial applications, these units provide optimal comfort while ensuring energy conservation and reliability.

One of the standout features of the Carrier 48EZ-A is its high-efficiency cooling system. With SEER ratings reaching up to 16, this model uses advanced compressor technology to ensure that energy consumption stays low while maximizing cooling output. The 48EZ-A incorporates a two-stage scroll compressor that enhances performance during partial load conditions, making it ideal for varying temperature demands throughout the day.

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Moreover, both models are equipped for easy installation and serviceability. The logical wiring design and access ports streamline maintenance, reducing downtime and optimizing overall performance. Additionally, they feature an energy-efficient fan design that maximizes airflow while minimizing energy use.

In summary, the Carrier 48EZ-A and 48VT-A rooftop units stand out in the HVAC market for their energy efficiency, advanced technology, and durable construction. These features make them ideal choices for various commercial applications where comfort, efficiency, and reliability are paramount. The combination of high-performance components and user-friendly features positions these models as leaders in modern HVAC solutions.
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