Carrier 69NT40-541-500 Operation And Service Manual
Also see for 69NT40-541-300: Operation and service
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Contents
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T-363 7–20b. To replace filter drier:1. Pump down the unit (refer to Section 7.4) and replace filter-drier.2. Evacuate the low side in accordance with Section 7.6.3. After unit is in operation, inspect for moisture in system and check charge.7.13 EVAPORATOR COIL & HEATER ASSEMBLYThe evaporator section, including the evaporator coil, should be cleaned regularly. The preferred cleaning fluid isfresh water or steam. Another recommended cleaner is Oakite 202 or similar, following manufacturer’s instructions.The two drain pan hoses are routed behind the condenser fan motor and compressor. The drain pan line(s) mustbe open to ensure adequate drainage.7.13.1 Evaporator Coil Replacementa. Pump unit down. (Refer to Section 7.4).WARNING!Always turn OFF the unit circuit breakers (CB-1 & CB-2) and disconnect main power supplybefore working on moving parts.b. With power OFF and power plug removed, remove the screws securing the panel covering the evaporatorsection (upper panel).c. Disconnect the defrost heater wiring.d. Remove the mounting hardware from the coil.e. Unsolder the two coil connections, one at the distributor and the other at the coil header.f. Disconnect the defrost temperature sensor (refer to Section 7.21) from the coil.g. Remove middle coil support.h. After defective coil is removed from unit, remove defrost heaters and install on replacement coil.i. Install coil assembly by reversing above steps.j. Leak check connections. Evacuate and add refrigerant charge.7.13.2 Evaporator Heater ReplacementThe heaters are wired directly back to the contactor and if a heater failure occurs during a trip, the heater set containingthat heater may be disconnected at the contactor.The next Pre-trip (P1) will detect that a heater set has been disconnected and indicate that the failed heater should bereplaced. To remove a heater, do the following:WARNING!Always turn OFF the unit circuit breakers (CB-1 & CB-2) and disconnect main power supplybefore working on moving parts.a. Before servicing unit, make sure the circuit breakers (CB-1 and CB-2) and start-stop switch (ST) are in theOFF position, and the power plug is disconnected.b. Remove the upper back panel.c. Determine which heater(s) need replacing by checking resistance of each heater set. Refer to Section 3.3for heater resistance values. Once the set containing the failed heater is determined, cut the splice connec-tion and retest to determine the actual failed heater(s).d. Remove hold-down clamp securing heater(s) to coil.e. Lift the bent end of the heater (with the opposite end down and away from coil). Move heater to the sideenough to clear the heater end support and remove.f. To replace a heater, do steps a through e in reverse. |
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