Carrier 38APS025 Manual

Also see for 38APD115: Installation instructions

Carrier 38APS025 Manual Manual pdf 31 page image

31Return Gas Temperature (RGT) — These sensors are factoryinstalled in a friction fit well located in the suction line of eachcircuit. The sensor is a 5,000 : at 77 F (25 C) thermistor con-nected to the main base board. These thermistors are used inthe suction superheat calculations. The thermistor must be in-sulated with cork tape insulation to reduce the effects of ambi-ent temperature on the sensor.Outdoor-air Temperature Sensor (OAT) — This sensor isfactory installed on a bracket which is inserted through thebase pan of the unit on unit sizes 025-060 (see the section Sen-sor Locations on page 32) or mounted to the back of the con-trol box on the unit sizes 065-130. This sensor is a 5,000 :thermistor at 77 F (25 C) connected to the main base board.Outside Air Temperature can be forced to a value at thescrolling marquee or Navigator device. To force the value, ac-cess the parameter TemperaturesoUNIToOAT. Pressto view the current value. Press again anduse the up and down arrow keys to display the desired value;then press to accept the value. On the scrolling mar-quee, the “.” in the lower right corner will flash. On the Navi-gator device, a flashing “f” will be displayed next to the value.To clear the forced value, press followed by the upand down arrow keys simultaneously. The value will revert tothe actual reading and the flashing “.” or “f” will be removed.Discharge Temperature Thermistor (DTT) — This sensor isonly used on units with a digital compressor. The sensor ismounted on the discharge line close to the discharge of the dig-ital compressor. The thermistor must be insulated with corktape insulation to reduce the effects of ambient temperature onthe sensor. It attaches to the discharge line using a spring clipand protects the system from high discharge gas temperaturewhen the digital compressor is used. This sensor is an86,000 : at 77 F (25 C) thermistor connected to the AUXboard (see Table 9).Space Temperature Sensor (T55, T56) — Space temperaturesensors are used to measure the interior temperature of a build-ing.Space Temperature can be forced to a value at the scrollingmarquee or Navigator device. To force the value, access theparameter TemperaturesoUNIToSPT. Press toview the current value. Press again and use the upand down arrow keys to display the desired value; then pressto accept the value. On the scrolling marquee, the “.”in the lower right corner will flash. On the Navigator device, aflashing “f” will be displayed next to the value. To clear theforced value, press followed by the up and down ar-row keys simultaneously. The value will revert to the actualreading and the flashing “.” or “f” will be removed.The following three types of SPT sensors are available:• Space temperature sensor (33ZCT55SPT) with timedoverride button (see Fig. 27)• Space temperature sensor (33ZCT56SPT) with timedoverride button and set point adjustment (see Fig. 28)• Space temperature sensor (33ZCT59SPT) with occu-pancy override button, space temperature offset, andLCD (liquid crystal display) display (see Fig. 29)All of the above sensors are 10,000 : at 77 F (25 C), Type IIthermistors and are connected to the low voltage terminal(LVT). The sensor should be mounted approximately 5 ft(1.5 m) from the floor in an area representing the average tem-perature in the space. Allow at least 4 ft (1.2 m) between thesensor and any corner. Mount the sensor at least 2 ft (0.6 m)from an open doorway.ENTER ENTERENTERENTERENTERENTERENTERENTER2 3 4 5 61SW1SENBRN (GND)BLU (SPT)RED(+)WHT(GND)BLK(-) CCN COMSENSOR WIRINGTIMED OVERRIDEBUTTON (SW1)Fig. 27 — Space Temperature SensorTypical Wiring (33ZCT55SPT)2 3 4 5 61SW1SEN SETCool WarmBRN (GND)BLU (SPT)RED(+)WHT(GND)BLK(-) CCN COMSENSOR WIRINGJUMPERTERMINALSAS SHOWNBLK(T56)TIMED OVERRIDEBUTTON (SW1)Fig. 28 — Space Temperature SensorTypical Wiring (33ZCT56SPT)222321LVTa38-7420Fig. 29 — Space Temperature SensorTypical Wiring (33ZCT59SPT)