Carrier 50KC04-06 Service And Maintenance Instructions

25Verify that the sensor’s Alarm and Trouble LEDs are now off.At the controller, clear its Alarm or Trouble state by pressingand holding the manual reset button (on the front cover) for 2seconds. Verify that the controller’s Alarm and Trouble LEDsare now off. Replace all panels.TROUBLESHOOTINGController’s Trouble LED is On1. Check the Trouble LED on each sensor connected to thecontroller. If a sensor’s Trouble LED is on, determine thecause and make the necessary repairs.2. Check the wiring between the sensor and the controller. Ifwiring is loose or missing, repair or replace as required.Controller’s Trouble LED is Flashing1. One or both of the sensors is 100% dirty.2. Determine which Dirty LED is flashing, then clean that sen-sor assembly as described in the detector cleaning section.Sensor’s Trouble LED is On1. Check the sensor’s Dirty LED. If it is flashing, the sensoris dirty and must be cleaned.2. Check the sensor’s cover. If it is loose or missing, securethe cover to the sensor housing.3. Replace sensor assembly.Sensor’s Power LED is Off1. Check the controller’s Power LED. If it is off, determinewhy the controller does not have power and make the nec-essary repairs.2. Check the wiring between the sensor and the controller. Ifwiring is loose or missing, repair or replace as required.Controller’s Power LED is Off1. Make sure the circuit supplying power to the controller isoperational. If not, make sure JP2 and JP3 are set correctlyon the controller before applying power.2. Verify that power is applied to the controller’s supplyinput terminals. If power is not present, replace or repairwiring as required.Remote Test/Reset Station’s Trouble LED Does Not FlashWhen Performing a Dirty Test, But the Controller’s TroubleLED Does1. Verify that the remote test/station is wired as shown inFig. 31. Repair or replace loose or missing wiring.2. Configure the sensor dirty test to activate the controller’ssupervision relay. See “Changing dirty sensor test” opera-tion on page 23.Sensor’s Trouble LED is On, But the Controller’s TroubleLED is OFFRemove JP1 on the controller.PROTECTIVE DEVICESCompressor ProtectionOVERCURRENTThe compressor has internal linebreak motor protection.OVERTEMPERATUREThe compressor has an internal protector to protect it againstexcessively high discharge gas temperatures.HIGH PRESSURE SWITCHThe system is provided with a high pressure switch mountedon the discharge line. The switch is stem-mounted and brazedinto the discharge tube. Trip setting is 630 psig ± 10 psig (4344± 69 kPa) when hot. Reset is automatic at 505 psig (3482 kPa).LOW PRESSURE SWITCHThe system is protected against a loss of charge and low evapo-rator coil loading condition by a low pressure switch located onthe suction line near the compressor. The switch is stem-mounted. Trip setting is 54 psig ± 5 psig (372 ± 34 kPa). Resetis automatic at 117 ± 5 psig (807 ± 34 kPa).EVAPORATOR FREEZE PROTECTIONThe system is protected against evaporator coil frosting andlow temperature conditions by a temperature switch mountedon the evaporator coil hairpin. Trip setting is 30°F ± 5°F (–1°C± 3°C). Reset is automatic at 45°F (7°C).SUPPLY (INDOOR) FAN MOTOR PROTECTIONDisconnect and lockout power when servicing fan motor. Thestandard supply fan motor is equipped with internal overcurrentand overtemperature protection. Protection devices reset auto-matically.The High Static option supply fan motor is equipped with a pi-lot-circuit Thermix combination overtemperature/overcurrentprotection device. This device resets automatically. Do not by-pass this switch to correct trouble. Determine the cause andcorrect it.CONDENSER FAN MOTOR PROTECTIONThe condenser fan motor is internally protected against over-temperature.Relief DeviceA soft solder joint at the suction service access port providespressure relief under abnormal temperature and pressure condi-tions (i.e., fire in building). Protect this joint during brazing op-erations near this joint.Control Circuit, 24-vThe control circuit is protected against overcurrent conditionsby a circuit breaker mounted on control transformer TRAN.Reset is manual.ELECTRIC HEATERSThe 50KC units may be equipped with field-installed accesso-ry electric heaters. The heaters are modular in design, withheater frames holding open coil resistance wires strung throughceramic insulators, line-break limit switches and a control con-tactor. One or two heater modules may be used in a unit.Heater modules are installed in the compartment below the in-door (supply) fan outlet. Access is through the indoor accesspanel. Heater modules slide into the compartment on tracksalong the bottom of the heater opening. See Fig. 34-36.Fig. 34 — Typical Access Panel LocationDISCONNECT MOUNTINGLOCATIONUNIT BLOCK-OFFPANELOUTDOORACCESS PANELINDOORACCESSPANEL