Carrier 48TCA04---A12 Service And Maintenance Instructions

58Supply Air Temperature (SAT) SensorThe supply air temperature sensor is a 3 K thermistorlocated at the inlet of the indoor fan. (See Fig. 75.) Thissensor is factory installed. The operating range oftemperature measurement is 0° to 158_F (--18_ to 70_C).See Table 15 for sensor temperature/resistance values.SUPPLY AIRTEMPERATURESENSORMOUNTINGLOCATIONSUPPLY AIRTEMPERATURESENSORC06033Fig. 75 -- Supply Air Sensor LocationThe temperature sensor looks like an eyelet terminal withwires running to it. The sensor is located in the “crimpend” and is sealed from moisture.Outdoor Air Lockout SensorThe EconoMi$er IV is equipped with an ambienttemperature lockout switch located in the outdoorairstream which is used to lock out the compressors belowa 42_F (6_C) ambient temperature. (See Fig. 70.)EconoMi$er IV Control ModesIMPORTANT: The optional EconoMi$er2 does notinclude a controller. The EconoMi$er2 is operated by a 4to 20 mA signal from an existing field-supplied controller(such as PremierLink™ control). See Fig. 72 for wiringinformation.Determine the EconoMi$er IV control mode before set upof the control. Some modes of operation may requiredifferent sensors. (See Table 22.) The EconoMi$er IV issupplied from the factory with a supply--air temperaturesensor and an outdoor-- air temperature sensor. This allowsfor operation of the EconoMi$er IV with outdoor air drybulb changeover control. Additional accessories can beadded to allow for different types of changeover controland operation of the EconoMi$er IV and unit.Outdoor Dry Bulb ChangeoverThe standard controller is shipped from the factoryconfigured for outdoor dry bulb changeover control. Theoutdoor air and supply air temperature sensors areincluded as standard. For this control mode, the outdoortemperature is compared to an adjustable setpoint selectedon the control. If the outdoor-air temperature is above thesetpoint, the EconoMi$er IV will adjust the outside airdampers to minimum position. If the outdoor-airtemperature is below the setpoint, the position of theoutside air dampers will be controlled to provided freecooling using outdoor air. When in this mode, the LEDnext to the free cooling setpoint potentiometer will be on.The changeover temperature setpoint is controlled by thefree cooling setpoint potentiometer located on the control.(See Fig. 76.) The scale on the potentiometer is A, B, C,and D. See Fig. 77 for the corresponding temperaturechangeover values.C06034Fig. 76 -- EconoMi$er IV Controller Potentiometerand LED LocationsLED ONLED ONLED ONLED ONLED OFF1918LED OFFLED OFFLED OFF1716151413121110940 45 50 55 60 65 70 75 80 85 90 95 100DEGREES FAHRENHEITmADCBAC06035Fig. 77 -- Outside Air Temperature ChangeoverSetpoints0510152025300.13 0.20 0.22 0.25 0.30 0.35 0.40 0.45 0.50STATIC PRESSURE (in. wg)FLOW IN CUBIC FEET PER MINUTE (cfm)C06031Fig. 78 -- Outdoor--Air Damper LeakageDifferential Dry Bulb ControlFor differential dry bulb control the standard outdoor drybulb sensor is used in conjunction with an additionalaccessory dry bulb sensor (part numberCRTEMPSN002A00). The accessory sensor must bemounted in the return airstream. (See Fig. 79.) Wiring is48TC