Carrier 38AKS008, 38AK007, 38AKS012, 38AKS009, 38AK008, 38AK012 Start-Up, Preliminary Checks

START-UP

Preliminary Checks

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

2.Check that all internal wiring connections are tight and that all barriers, covers, and panels are in place. Ensure no electrical wires are in contact with refrigerant tubing.

3.Ensure all service valves are open. On 38AKS units, be sure all compressor service valves are backseated.

4.Verify that compressor holddown bolts for units 38AKS have been loosened and that flat/snubber washers can be rotated by applying finger pressure (snug, but not tight).

5.Verify compressor crankcase heater is securely in place. Crankcase heater must operate for at least 24 hours before start-up. The 38AK unit size 007 does not require a crankcase heater.

6.Note that compressor oil level is visible in the sight glass (38AKS units only).

7.Check for leaks in refrigerant system by using soap bub- bles and/or electronic leak detector.

8.Check that liquid line solenoid valve is located at evapo- rator coil as shown in Filter Drier and Moisture Indicator section, page 6.

9.Check voltage imbalance as shown in Table 5, Note 2.

10.Check that both outdoor and indoor units are properly mounted in accordance with installation instructions and applicable codes.

Compressor Rotation — On 3-phase units with scroll compressors, it is important to be certain compressor is rotating in the proper direction. To determine whether or not compres- sor is rotating in the proper direction:

1.Connect service gages to suction and discharge pressure fittings.

2.Energize the compressor.

3.The suction pressure should drop and the discharge pres- sure should rise, as is normal on any start-up.

If the suction pressure does not drop and the discharge pressure does not rise to normal levels:

1.Note that the condenser fan is probably also rotating in the wrong direction.

2.Turn off power to the unit, tag disconnect.

3.Reverse any two of the unit power leads.

4.Reapply power to the compressor, verify correct pressures.

The suction and discharge pressure levels should now move to their normal start-up levels.

Evacuate and Dehydrate — Evacuate and dehydrate entire refrigerant system by use of the methods described in Carrier GTAC II, Module 4, System Dehydration. Evacuate system down to 500 microns and ensure vacuum hold for 15 minutes. If vacuum does not hold, pressurize system and locate leak and repair.

Refrigerant Charge — Refer to Carrier GTAC II, Module 5, Charging Recovery, Recycling, and Reclamation.

Unit panels must be in place when unit is operating during charging procedure.

Unit is shipped with holding charge only. Weigh in 7 lb (3 kg) of R-22 to start unit.

CHARGE COOLING — Use Cooling Charging Charts, Fig. 8A or 8B and 9A or 9B. Unit must be charged in cooling mode only. Vary refrigerant until the conditions of the chart are

met. Note that charging charts are different from type normally used. Charts are based on charging the units to the correct sub- cooling for the various operating conditions. Accurate pressure gage and temperature sensing device are required. Connect the pressure gage to the service port on the liquid line service valve. Mount the temperature sensing device on the liquid line, close to the liquid line service valve and insulate it so that out- door ambient temperature does not affect the reading. Indoor airflow must be within the normal operating range of the unit.

Operate unit a minimum of 15 minutes. Ensure pressure and temperature readings have stabilized. Plot liquid pressure and temperature on chart and add or reduce charge to meet curve. Adjust charge to conform with charging chart, using liquid pressure and temperature to read chart.

Fig. 8A — Cooling Charging Chart — 38AK007

(60 Hz)

Fig. 8B — Cooling Charging Chart — 38AK007

(50 Hz)

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