SERVICE
Protection Devices
OIL PRESSURE SWITCH (OPS) — The oil pressure switch protects against damage from loss of oil or loss of oil pressure during unit
The switch time delay is approximately 45 seconds. If after
45 seconds the oil pressure differential sensed by the OPS is less than 11 psig, the heater remains energized. The OPS temperature actuated switch then opens and the compressor is deenergized. If the differential reaches 11 psig, the OPS opens and deenergizes the heater and the system operates normally. See Table 4.
IMPORTANT: If the oil pressure switch causes unit lock- out, determine and correct the cause of the lockout (such as loss of compressor oil or flooded compressor) before restarting the unit. Failure to correct the cause of OPS lockout may constitute abuse. Equipment failure due to abuse is not covered by warranty.
To restart the unit, push the OPS reset button and then push the control circuit switch on the unit control box to OFF and then to ON.
Table 4 — Factory Switch Settings
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| PRESSURE CHANGE AFFECTING | |||
SWITCH TYPE | SWITCH POSITION (psig) | ||||
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| Closed | Open | ||
High Pressure | 210 | (±10) | 290 | (±10) | |
Low Pressure | 70 | (±4) | 60 | (±4) | |
Oil Pressure |
| 6 | 11 |
NOTES:
1.Values for the high- and
2.Values for oil pressure are above operating suction pressure (pressure differential between suction and discharge pressures of oil pump).
TIME GUARD® CONTROL — The Time Guard control protects against short cycling. See Start Compressor.
CRANKCASE HEATER — The crankcase heater prevents absorption of liquid refrigerant by oil in crankcase during brief or extended shutdown periods. Source of
IMPORTANT: Never open any switch or disconnect that will deenergize the crankcase heater unless unit is being serviced or is to be shut down for a prolonged period. After a prolonged shutdown or a service job, energize the crank- case heater for 24 hours before starting the compressor.
Compressor Thermal Protection — A discharge temperature sensor, installed in one cylinder head, detects an overtemperature condition. If the discharge temperature
exceeds 295 ± 5 F, the sensor contacts open and the compressor shuts down. The sensor reset temperature is 235 F minimum. See Fig. 8 for control circuit connections.
Capacity Control System
CAPACITY CONTROL VALVE (Fig. 9) — Valve is con- trolled by suction pressure and actuated by discharge pressure. Each valve controls 2 cylinders. On
IMPORTANT: Do not use automatic pumpdown control on 06E,07E units equipped with unloader valves. Use single pumpout or solenoid drop (minimum protection) control.
CAPACITY CONTROL VALVE ADJUSTMENTS
Control Set Point (Cylinder Load Point) — Adjustable from 0 to 86 psig. Pressure differential between cylinder
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| CR |
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| 4 | 6 | RED | C1 C2 C2 | YEL | C2 C1 |
| BLU |
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TIMER | B2 |
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| DTS |
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B | ORN |
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| BLU |
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CONTACTS |
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| B1 |
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| TB2 | 6 |
LEGEND
C— Compressor Contactor CR — Control Relay
DTS — Discharge Temperature Sensor TB — Terminal Block
•Splice (in compressor junction box)
Fig. 8 — Discharge Temperature Sensor (DTS)
CONTROL
SET POINT
ADJUSTMENT
NUT
VALVE BODY
SEALING CAP
(COVERS PRESSURE DIFFERENTIAL
ADJUSTMENT SCREW)
Fig. 9 — Capacity Control Valve
9