High pressure lock-out.
- Dirty condenser.
- Excessive refrigerant charge on nonreceiver.
- High suction pressure
- High/low voltage, high amperage on 3 phase supply, voltage out of balance.
Low pressure lock-out.
- Low-refrigerant flow (see section on “high superheat”).
- Low air flow thru evaporator.
- Low outside temperature
- Partial load, low humidity, , without capacity control.
- Evaporator discharge air recirculating.
- Liquid line solenoid leaking during the off cycle.
- Compressor valve leaking during the off cycle.
- Undercharged system.
- TEV problems
Uninsulated receiver exposed to low ambient.
Find source of problem and take corrective action.
Insulate and/or artificially heat receiver.