Carrier Comfort 48VT Owner's Information Manual

42. Close the external manual shutoff valve.3. Turn off the electrical power supply to the unit.4. Remove the control access panel. (See Fig. 2.)5. Move the selector switch on the internal gas valve to theOFF position.6. Replace the control access panel.To start unit electric cooling:Refer to Fig. 6 while proceeding with the following steps.1. Set the temperature selector on room thermostat to highesttemperature setting and set system SWITCH to OFF.2. Close the external manual shutoff valve, if not alreadyclosed.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. 7 while proceeding with the following steps.1. Set the temperature selector on room thermostat to highesttemperature setting and set system SWITCH to OFF.2. Close the external manual shutoff valve, if not alreadyclosed.3. Turn off the electrical power supply to the unit.NOTE: Heat Pump heating mode procedure is similar to electriccooling mode except thermostat mode is HEAT and thermostatmust operate on first stage heating above the balance point that hasbeen determined by the Dealer.OPERATING YOUR UNITThe operation of your unit is controlled by the indoor temperaturecontrol (thermostat). You simply adjust the thermostat and itmaintains the indoor temperature at the level you select. Mostthermostats of heating and cooling systems have 3 controls: atemperature control selector, a FAN control, and a SYSTEM orMODE control. Refer to your thermostat owner’s manual for moreinformation.To better protect your investment and to eliminate unnecessaryservice calls, familiarize yourself with the following facts:1. During heat pump heating, increasing the thermostat settingmore than 2_F (1.1_C) may cause the supplemental gas heatto be turned on for a short period of time to satisfy thethermostat. Needless use of the supplementary heat reducespotential energy savings.2. Ice or frost tends to form on the coil during winter heatingoperation. Your heat pump is designed to automatically meltthe ice. When in this defrost cycle, it is normal for steamor fog to rise from the outdoor unit. Do not be alarmed!Cooling ModeWith the SYSTEM control set to COOL, your unit will run incooling mode until the indoor temperature is lowered to the levelyou have selected. On extremely hot days, your unit will run forlonger periods at a time and have shorter “off” periods than onmoderate days.Heat Pump Heating ModeWith the SYSTEM or MODE control of your indoor thermostat setto HEAT, your unit will run in heat pump heating mode until roomtemperature is raised to the level you have selected. Of course, yoursystem will run for longer periods to maintain a comfortableenvironment on cooler days and nights than on moderate ones.Gas Heat ModeYour heat pump is your primary heating source. Your system isalso equipped with a supplemental gas heating source. On colddays and nights, your system will automatically turn on thesupplemental heat in order to maintain the level of comfort youhave selected.When your heat pump needs additional heat to keep youcomfortable, your thermostat will turn on the supplemental gasheat.