Carrier 38HDR018-060, 38HDF018-036 Preliminary Checks, Condenser-Fan Mounting Positions

START-UP

Preliminary Checks

1.Check that all internal wiring connections are tight and that all barriers, covers, and panels are in place.

2.Field electrical power source must agree with unit name- plate rating.

3.All service valves must be open.

4.Belly-band crankcase heater must be tight on compressor crankcase for those units with belly-band heaters.

Leak Test — Field piping and fan coil must be leak tested by pressure method. Use R-410A at approximately 25 psig backed up with an inert gas to a total pressure not to exceed 245 psig.

Leak detectors should be designed to detect HFC (hydro- fluorocarbon) refrigerant.

Evacuate and Dehydrate — Field piping and fan coil must be evacuated and dehydrated.

Charge System — Release charge into system by open- ing (backseating) liquid and suction line service valves. Refer to separate indoor unit installation instructions for the required total system charge when connected to 25 ft of tubing.

To Start Unit — Be sure that the field disconnect is closed. Set room thermostat below ambient temperature. Oper- ate unit for 15 minutes, then check system refrigerant charge. See Refrigerant Charging section on page 12.

NOTE: When using in conjunction with 40QA or 40QK fan coils, refer to start-up instructions included with fan coil for correct start-up procedures.

SERVICE

Before performing recommended maintenance, be sure unit main power switch is turned off. Failure to do so may result in electrical shock or injury from rotating fan blade.

Outdoor Fan — A reinforced wire mount holds the out- door fan assembly in position. See Fig. 8 for proper mounting position.

38HDF UNIT SIZE, in.

	018-030		036
	0.433		0
	38HDR UNIT SIZE, in.
018,024		030,036		048,060
0.433		0		0

Fig. 8 — Condenser-Fan Mounting Positions

High-Pressure Relief Valve — The high-pressure re- lief valve is located in the compressor. The relief valve opens at a pressure differential of approximately 550 to 625 ± 50 psid between suction (low side) and discharge (high side) to allow pressure equalization.

Internal Current and Temperature Sensitive Overload — The control resets automatically when internal compressor motor temperature drops to a safe level (overloads may require up to 45 minutes to reset). When an internal overload is suspected of being open, check by using an ohmmeter or continuity tester.

Pumpdown Procedure — The system may be pumped down in order to make repairs on the low side without losing complete refrigerant charge.

Never open system to atmosphere while it is under a vac- uum. Equipment damage may result.

When system must be opened for service, recover refriger- ant, break vacuum with dry nitrogen before opening system.

1.Attach pressure gage to suction service valve gage port.

2.Frontseat the liquid/mixed phase line valve.

The 38HDC unit coils hold only the factory-designated amount of refrigerant. Additional refrigerant may cause units to relieve pressure through the compressor internal pressure relief valve (indicated by a sudden rise of suction pressure) before suction pressure reaches 5 psig. If this occurs, shut off unit immediately then frontseat the suction valve and remove and recover excess refrigerant following accepted practices. Equipment damage may result.

3.Start unit and run until suction pressure reaches 20 psig.

4.Shut unit off and frontseat suction valve.

5.Depressurize low side of unit and recover refrigerant following accepted practices.

High-Pressure Switch — The high-pressure switch, located on discharge line, protects against high discharge pressures caused by such events as overcharge, condenser-fan motor failure, system restriction, etc. It opens on pressure rise at about 650 ± 10 psig. If system pressures go above this setting during abnormal conditions, the switch opens.

DO NOT attempt to simulate these system abnormalities

— high pressures pose a serious safety hazard.

The high-pressure switch is checked with an ohmmeter. If system pressure is below 625 psig switch shows continuity.

Crankcase Heater — The crankcase heater prevents refrigerant migration and compressor oil dilution during shutdown when compressor is not operating. If the crankcase heater is deenergized for more than 6 hours, both compressor service valves must be closed.

NOTE: Crankcase heaters are only available on 38HDR030- 060 units.

The crankcase heater is powered by the high-voltage power of the unit. It is connected across the line side of the contactor and is thermostatically controlled.

Use extreme caution when troubleshooting this device, as line voltage is continually present. Serious personal injury could result.

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