To Regulate Control Set Point — Turn adjustment nut
clockwise to its bottom stop. In this position, set point is 86 psig. Control set point is then regulated to desired pressure by turning adjustment nut counterclockwise. Each full turn decreases set point by approximately 7.2 psi. Approximately
12 turns counterclockwise | lowers the control | set | point to | ||||||
0 psig. See Table 5. |
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Table 5 — Capacity Control |
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| % Full Load Capacity | ||||||
| NO. OF | 100 |
| 67 |
| 49 |
| 32 | |
UNIT 06E,07E | CONTR |
| % Full Load kW | ||||||
| CYL |
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| 100 |
| 73 |
| 57 |
| 46 | ||
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| Number of Active Cylinders | ||||||
ALL 4 CYLINDER | 2 |
| 4 |
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| 2 |
| — |
MODELS |
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ALL 6 CYLINDER | 4 |
| 6 |
| 4 |
| — |
| 2 |
MODELS |
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NOTE: Capacity control valve factory settings for
are: 59 psig control set point (cylinder load point), 10 psi differential
(59 psig cylinder unload point). Settings for
Pressure Differential Adjustment — Turn differential adjust- ing screw counterclockwise to its
SUCTION CUTOFF UNLOADER OPERATION — The ca- pacity control valve shown in Fig. 9 is the pressure operated type. Refer to Fig. 10 and the following description for valve operation.
Loaded — When suction pressure rises high enough to over- come control set point spring, the diaphragm snaps to the left and relieves pressure against the poppet valve. The drive spring moves poppet valve to the left and it seats in the closed position. See Fig. 10.
With poppet valve closed, discharge gas is directed into the
Unloaded — As suction pressure drops below set point, con- trol spring expands, snapping diaphragm to right. This forces poppet valve open and allows gas from discharge manifold to vent thru base of control valve to suction side. Loss of full discharge pressure against unloader piston allows unloader valve spring to move valve left to closed position. The suction port is blocked, isolating the cylinder bank from the suction manifold. The cylinder bank is now unloaded. See Fig. 10.
Service Replacement Compressors — These compressors are not equipped with capacity control valves. One
Replacing Suction Cutoff Unloading Heads — When the original compressor is equipped with suction cutoff unloading head(s), the complete cylinder head and control valve assem- blies must be transferred to the service (replacement) compres- sor. See Fig. 10 for typical suction cutoff installation. Where one step of unloading is required, remove the
Be sure the new cylinder head gasket is the one shown in Fig. 11, Item 33, when installing suction cutoff unloader head.
Install parts removed from replacement compressor on original compressor and seal all openings to prevent contamination.
Removing, Inspecting and Replacing Components (Fig. 11)
Do not remove the compressor terminal box cover until all electrical power is disconnected and pressure is relieved. Terminal pins may blow out causing injuries, death, and/or fire.
SERVICE NOTES
1.All compressors have interchangeable valve plate assem- blies, unloader valves and oil pump bearing head assemblies. For replacement items use Carrier Specified Parts.
2.Before compressor is opened, the refrigerant must be removed from it by the Pumpdown method:
a.Start compressor, close suction shutoff valve, and reduce crankcase pressure to 2 psig. (Bypass low pressurestat with a jumper.)
b.Stop compressor and isolate from system by closing discharge shutoff valve.
c.Bleed any residual refrigerant. Drain oil if necessary.
3.After disassembly, clean all parts with solvent. Use mineral spirits, white gasoline or naphtha.
4.Before assembly, coat all parts with compressor oil and clean and inspect all gasket surfaces. Replace all gaskets with new
5.After reassembly, evacuate compressor and open suction and discharge valves. Restart compressor and adjust refrigerant charge.
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