Protective Devices, Cooling Charging Chart

								BOTH CIRCUITS
				ALL OUTDOOR FANS MUST BE OPERATING
(DEG F)	140
	140


VALVE	120
			ADD		CHARGE		IF ABOVE CURVE
LIQUIDAT	100
LIQUIDAT
TEMPERATURELIQUID
	80




	60								REDUCE CHARGE IF BELOW CURVE


	40

		100				150	200			250	300	350	400
	50	100				150	200			250	300	350	400

LIQUID PRESSURE AT LIQUID VALVE (PSIG)

Fig. 36 — Cooling Charging Chart

MOISTUREMISER SYSTEM CHARGING — The system charge for units with the MoistureMiser option is greater than that of the standard unit alone. The charge for units with this option is indicated on the unit nameplate drawing. To charge systems using the MoistureMiser Dehumidification package, fully evacuate, recover, and re-charge the system to the name- plate specified charge level. To check or adjust refrigerant charge on systems using the MoistureMiser Dehumidification package, charge per the standard subcooling charts. The sub- cooler MUST be deenergized to use the charging charts. The charts reference a liquid pressure (psig) and temperature at a point between the condenser coil and the subcooler coil. A tap is provided on the unit to measure liquid pressure entering the subcooler (leaving the condenser).

Filter Drier — Replace whenever refrigerant system is ex- posed to atmosphere.

Protective Devices

COMPRESSOR PROTECTION

Overcurrent — Each compressor has internal line break motor protection, except the circuit no. 1 on the 50TJ028 unit. Com- pressor no. 1 on the 50TJ028 unit uses an electronic module lo- cated with the compressor junction box, to provide motor pro- tection. This electronic module monitors winding and dis- charge temperatures. If these temperatures reach the trip values, the module interrupts the control line and causes the compressor to switch off.

Crankcase Heater — Only the 50TJ028 unit and units with the optional MoistureMiser Dehumidification system are equipped with a 70-watt crankcase heater to prevent absorption of liquid refrigerant by oil in the crankcase when the compres- sor is idle. The crankcase heater is energized whenever there is a main power to the unit and the compressor is not energized.

IMPORTANT: After prolonged shutdown or servicing, energize the crankcase heaters for 24 hours before start- ing the compressors.

Compressor Lockout — If any of the safeties (high-pressure, low-pressure, freeze protection thermostat, compressor internal thermostat) trip, or if there is loss of power to the compressors, the CLO (compressor lockout) will lock the compressors off. To reset, manually move the thermostat setting.

EVAPORATOR FAN MOTOR PROTECTION — A manu- al reset, calibrated trip, magnetic circuit breaker protects against overcurrent. Do not bypass connections or increase the size of the breaker to correct trouble. Determine the cause and correct it before resetting the breaker.

CONDENSER-FAN MOTOR PROTECTION — Each condenser-fan motor is internally protected against overtemperature.

HIGH- AND LOW-PRESSURE SWITCHES — If either switch trips, or if the compressor overtemperature switch acti- vates, that refrigerant circuit will be automatically locked out by the CLO. To reset, manually move the thermostat setting.

FREEZE PROTECTION THERMOSTAT (FPT) — An FPT is located on the top and bottom of the evaporator coil. It de- tects frost build-up and turns off the compressor, allowing the coil to clear. Once the frost has melted, the compressor can be reenergized.

Relief Devices — All units have relief devices to protect against damage from excessive pressures (e.g., fire). These de- vices protect the high and low side.

Control Circuit, 24-V — This control circuit is protect- ed against overcurrent by a 3.2-amp circuit breaker. Breaker can be reset. If it trips, determine cause of trouble before resetting.

Replacement Parts — A complete list of replacement parts may be obtained from any Carrier distributor upon request.

EconoMi$er LEDs — The EconoMi$er control module has an LED for diagnostic purposes. The flash code identifica- tion is shown in Table 15.

Optional Hinged Access Doors — When the optional service package is ordered or the if the hinged access doors option is ordered, the unit will be provided with external and internal hinged access doors to facilitate service.

Four external hinged access doors are provided. All external doors are provided with 2 large 1/4 turn latches with folding bail-type handles. (Compressor access doors have one latch.) A single door is provided for filter and drive access. One door is provided for control box access. The control box access door is interlocked with the non-fused disconnect which must be in the OFF position to open the door. Two doors are provided for ac- cess to the compressor compartment.

Two internal access doors are provided inside the filter/ drive access door. The filter access door (on the left) is secured by 2 small 1/4 turn latches with folding bail-type handles. This door must be opened prior to opening the drive access door. The drive access door is shipped with 2 sheet metal screws holding the door closed. Upon initial opening of the door, these screws may be removed and discarded. The door is then held shut by the filter access door, which closes over it.