Carrier 48EZ-A, 48VT-A Operating Your Unit, Cooling Mode, Heat Pump Heating Mode, Gas Heat Mode

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11.Set the temperature selector on room thermostat to desired setting.

!WARNING

FIRE AND EXPLOSION HAZARD

Failure to follow this warning could result in personal injury, death, and/or property damage.

1.If the main burners fail to light, or the blower fails to start, shut down gas heating section and call your dealer for service.

2.Never attempt to manually light the main burners on unit with a match, lighter, or any other flame. If the electric sparking device fails to light the main burners, refer to the following shutdown procedures, then call your dealer as soon as possible.

Flue Hood

Burners Gas Valve

A09043

Fig. 4 - Gas Heating/Electric Cooling Unit with Access Panel

Removed

To shut off unit gas heat:

!WARNING

FIRE, EXPLOSION, ELECTRICAL SHOCK HAZARD

Failure to follow this warning could result in personal injury, death, and/or property damage.

Do not turn off the electrical power to unit without first turning off the gas supply.

NOTE: If the unit is being shut down because of a malfunction, call your dealer as soon as possible.

Should overheating occur or the gas supply fail to shut off, shut off the external manual gas valve to the unit before shutting off the electrical supply. Do not use this unit if any part has been under water. Immediately call a qualified service technician to inspect the unit and to replace any part of the control system and any gas control which has been under water.

Refer to Fig. 6 while proceeding with the following steps.

1.Set the temperature selector on room thermostat to lowest temperature setting and set system SWITCH to OFF.

2.Close the external manual shutoff valve.

3.Turn off the electrical power supply to the unit.

4.Remove the control access panel. (See Fig. 3.)

5.Move the selector switch on the internal gas valve to the OFF position.

6.Replace the control access panel.

To start unit electric cooling:

Refer to Fig. 7 while proceeding with the following steps.

1.Set the temperature selector on room thermostat to highest temperature setting and set system SWITCH to OFF.

2.Close the external manual shutoff valve, if not already closed.

3.Turn ON the electrical power supply to the unit.

4.Set system switch to COOL.

5.Set the temperature selector on room thermostat slightly be- low the room temperature to start unit.

To shut off unit electric cooling:

Refer to Fig. 8 while proceeding with the following steps.

1.Set the temperature selector on room thermostat to highest temperature setting and set system SWITCH to OFF.

2.Close the external manual shutoff valve, if not already closed.

3.Turn off the electrical power supply to the unit.

NOTE: Heat Pump heating mode procedure is similar to electric cooling mode except thermostat mode is HEAT and thermostat must operate on first stage heating above the balance point that has been determined by the Dealer.

OPERATING YOUR UNIT

The operation of your unit is controlled by the indoor temperature control (thermostat). You simply adjust the thermostat and it maintains the indoor temperature at the level you select. Most thermostats of heating and cooling systems have 3 controls: a temperature control selector, a FAN control, and a SYSTEM or MODE control. Refer to your thermostat owner’s manual for more information.

To better protect your investment and to eliminate unnecessary service calls, familiarize yourself with the following facts:

1.During heat pump heating, increasing the thermostat setting more than 2_F (1.1_C) may cause the supplemental gas heat to be turned on for a short period of time to satisfy the thermostat. Needless use of the supplementary heat reduces potential energy savings.

2.Ice or frost tends to form on the coil during winter heating operation. Your heat pump is designed to automatically melt the ice. When in this defrost cycle, it is normal for steam or fog to rise from the outdoor unit. Do not be alarmed!

Cooling Mode

With the SYSTEM control set to COOL, your unit will run in cooling mode until the indoor temperature is lowered to the level you have selected. On extremely hot days, your unit will run for longer periods at a time and have shorter “off” periods than on moderate days.

Heat Pump Heating Mode

With the SYSTEM or MODE control of your indoor thermostat set to HEAT, your unit will run in heat pump heating mode until room temperature is raised to the level you have selected. Of course, your system will run for longer periods to maintain a comfortable environment on cooler days and nights than on moderate ones.

Gas Heat Mode

Your heat pump is your primary heating source. Your system is also equipped with a supplemental gas heating source. On cold days and nights, your system will automatically turn on the supplemental heat in order to maintain the level of comfort you have selected.

When your heat pump needs additional heat to keep you comfortable, your thermostat will turn on the supplemental gas

heat.

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Contents 48VT-A 48EZ-A Without Economizer 48VT-A Without Economizer48EZ-A With Economizer 48VT-A with Economizer FIRE, EXPLOSION, Electrical Shock Hazard Safety ConsiderationsCUT Hazard Unit Introduction Starting or Shutting Off UnitFire and Explosion Hazard Electrical Shock HazardCooling Mode Heat Pump Heating ModeGas Heat Mode Operating Your UnitMain Main Maintenance and Service Defrost ModeEmergency Heat Mode Routine MaintenanceReplacing or inspecting filters in units with economizers Small Chassis See FigLarge Chassis See Fig Fans and Fan MotorsElectrical Controls and Wiring Refrigerant CircuitUnit Panels Combustion Area and Vent SystemCase of Trouble Before you call for serviceIf insufficient heating or cooling is suspected
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48VT-A, 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.

Meanwhile, the Carrier 48VT-A is designed with variable speed technology that allows for precise modulation of airflow and cooling capacity, adapting seamlessly to real-time building conditions. This technology not only improves comfort but also significantly reduces energy usage by optimizing operational efficiency.

Both units are equipped with advanced microprocessor controls that facilitate superior management of the HVAC system. The controls offer programmable options allowing for enhanced control over system operation, scheduling, and diagnostics. This promotes easy maintenance and ensures long-term reliability.

In terms of construction, the Carrier 48EZ-A and 48VT-A units are built with corrosion-resistant materials, ensuring durability and longevity even in challenging environments. The cabinet is designed with insulated panels to minimize sound levels, making them suitable for installation in noise-sensitive locations.

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.