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Table 37 — Troubleshooting
SYMPTOMS CAUSE REMEDY
Compressor Cycles
Off on Loss of Charge
Loss of charge control. Acting erratically. Repair leak and recharge.
Replace control.
Low refrigerant charge Add refrigerant.
Low suction temperature Raise cooler leaving fluid temperature set point.
Compressor Cycles Off on Out
of Range Condition
Thermistor failure Replace thermistor.
System load was reduced faster than controller could
remove stages
Unit will restart after fluid temperature rises back into the
control band. Avoid rapidly removing system load or
increase loop volume.
Temperature controller deadband setting is too low Raise deadband setting.
Compressor Shuts Down on
High-Pressure Control
High-pressure control acting erratically Replace control.
Noncondensables in system Purge system.
Condenser scaled/dirty Clean condenser.
Fans in remote condensing unit (30MPA only) not operating Repair or replace if defective.
System overcharged with refrigerant Reduce charge.
Unit Operates Too Long
or Continuously
Low refrigerant charge Add refrigerant.
Control contacts fused Replace control.
Air in system Purge system.
Partially plugged or plugged expansion valve or filter drier Clean or replace as needed.
Defective insulation Replace or repair as needed.
Service load Keep doors and windows closed.
Damaged compressor Check compressor and replace if necessary.
Unusual or Loud System
Noises
Piping vibration Support piping as required.
Check for loose pipe connections or damaged compressor
Expansion valve hissing Add refrigerant.
Check for plugged liquid line filter drier.
Compressor noisy Replace compressor (worn bearings).
Check for loose compressor holddown bolts.
Compressor Loses Oil Leak in system Repair leak.
Mechanical damage (Failed seals or broken scrolls) Replace compressor.
Oil trapped in line Check piping for oil traps.
Hot Liquid Line Shortage of refrigerant due to leak Repair leak and recharge.
Frosted Liquid Line Restricted filter drier Replace filter drier.
Frosted Suction Line Expansion valve admitting excess refrigerant (note: this is a
normal condition for brine applications)
Replace valve if defective.
Stuck TXV Replace valve if defective.
Freeze-Up Improper charging Make sure a full quantity of fluid is flowing through the cooler
while charging, and suction pressure in cooler is equal to or
greater than pressure corresponding to 32 F (0° C).
System not drained for winter shutdown Recommended that system be filled with an appropriate gly-
col mixture to prevent freezing of pumps and fluid tubing.
Loose Thermistor Verify thermistors are fully inserted in wells.