START-UP
Compressor crankcase heater must be on for 24 hours before start-up. After the heater has been on for 24 hours, the unit can be started. If no time has elapsed since the pre- liminary charge step has been completed, it is unnecessary to wait the 24-hour period.
Preliminary Checks
1.Ensure that compressor service valves are backseated.
2.Verify that each compressor ¯oats freely on its mounting springs.
3.Check that electric power supply agrees with unit name- plate data.
4.Verify that compressor crankcase heater is securely in place.
5.Check that compressor crankcase heater has been on at least 24 hours.
6.Note that compressor oil level is visible in the sight glass.
7.Recheck for leaks using same procedure as pre- viously outlined in Pre-Start-Up section, Leak Test and Dehydration.
8.If any leaks are detected, evacuate and dehydrate as pre- viously outlined in Pre-Start-Up section, Leak Test and Dehydration.
9.All internal wiring connections must be tight, and all bar- riers and covers must be in place.
Preliminary Oil Charge Ð Compressor is factory charged with oil (see Tables 1A-1D). When oil is checked at start-up, it may be necessary to add or remove oil to bring it to the proper level. One recommended oil level adjust- ment method follows:
ADD OIL Ð Close suction service valve and pump down crankcase to 2 psig (14 kPag). (Low-pressure switch must be jumpered.) Wait a few minutes and repeat until pressure remains steady at 2 psig (14 kPag). Remove oil ®ll plug above the oil level sight glass, add oil through plug hole, and replace plug. Run compressor for 20 minutes and check oil level. See Fig. 9.
NOTE: Use only Carrier approved compressor oil. Ap- proved sources are:
Petroleum Specialties Inc. . . . . . . . . . . . . . . . . Cryol 150A Texaco, Inc. . . . . . . . . . . . . . . . . . . . . . . . . . Capella WF-32 Witco Chemical Co. . . . . . . . . . . . . . . . . . . . . . Suniso 3GS
Do not use oil that has been drained out, or oil that has been exposed to atmosphere.
REMOVE OIL Ð Pump down compressor to 2 psig (14 kPag). Loosen the 1¤4-in. (6.4 mm) pipe plug at the com- pressor base and allow the oil to seep out past the threads of the plug.
NOTE: The crankcase will be slightly pressurized. Do not remove the plug, or the entire oil charge will be lost.
Small amounts of oil can be removed through the oil pump discharge connection while the compressor is running.
Start Unit Ð The ®eld disconnect is closed, the fan cir- cuit breaker is closed, and the space thermostat is set above ambient so that there is no demand for cooling. Only the crankcase heater will be energized.
Next, close the compressor circuit breaker and then reset space thermostat below ambient so that a call for cooling is ensured. If compressor does not start, set thermostat lower.
NOTE: Do not use circuit breaker to start and stop the com- pressor except in an emergency.
After starting, there is a delay of at least 3 seconds before compressor starts.
Never charge liquid into the low-pressure side of sys- tem. Do not overcharge. During charging or removal of refrigerant, be sure indoor-fan system is operating.
Adjust Refrigerant Charge
NOTE: Actual start-up and all refrigerant charge modi®ca- tions should be done only under supervision of a quali®ed refrigeration mechanic.
With all fans operating, adjust the refrigerant charge in accordance with the unit charging charts located on the inside of the control box doors and in Fig. 10-12.
Measure pressure at the liquid line service valve, being sure Schrader depressor is used if required. Also, measure liquid line temperature as close to the liquid service valve as possible. Add charge until the pressure and temperature con- ditions of the charging chart curve are met. If liquid pressure and temperature point fall above curve, add charge. If liquid pressure and temperature point fall below curve, reduce the charge until the conditions match the curve.
If the sight glass is cloudy, check refrigerant charge again. Ensure all fans are operating. Also ensure maximum allowable liquid lift has not been exceeded. If charged per chart and if the sight glass is still cloudy, check for a plugged ®lter drier or a partially closed solenoid valve. Replace or repair, as needed.
Check Compressor Oil Level Ð After adjusting the refrigerant charge, allow the compressor to run fully loaded for 20 minutes. Running oil level should be within view of the crankcase sight glass. Stop the compressor at the ®eld power supply disconnect and check the crankcase oil level. Add oil only if necessary to bring the oil into view in the sight glass. If oil is added, run the compressor for an addi- tional 10 minutes, then stop and check oil level. If the level remains low, check the piping system for proper design for oil return; also, check the system for leaks.
If the initial check shows too much oil (too high in the sight glass) remove oil to proper level. See Preliminary Oil Charge, this page, for proper procedure for adding and removing oil. See Fig. 9.
When the above checks are complete, repeat the proce- dure with the unit operating at minimum load conditions.
Unload the compressor by turning the control set point adjustment nut counterclockwise until the adjustment nut stops. The unloader is now at 0 psig (0 kPag) set point. If electric actuated unloaders are installed, energize the solenoid to un- load the compressor.
Return unloader to original setting after checks are complete.
38AKS024 | 38AKS013,014,016 |
(06E COMPRESSOR) | (06D COMPRESSOR) |
Fig. 9 Ð Operating Oil Levels
Final Checks Ð Ensure all safety controls are operat- ing, control panel covers are on, and the service panels are in place.
