CLO (COMPRESSOR LOCK-OUT) in air conditioning

 The CLO is a protection device against automatic compressor cycling when shutting down by safety elements (high or low pressure switch, Line Break, internal thermostat and overload relay). It is located inside the electrical panel of the condensing units.

The CLO monitors the current that passes through the sensor loop, whether or not triggering a relay if the logic condition is false or true. After shutdown by the protection device, the CLO prevents automatic restarting when the situation normalizes, thus preventing the compressor from cycling. A current below 4A ± 1 through the sensor loop opens the normally closed contact between terminals 2 and 3 of the CLO. Terminals 1 and 2 are for the 24V ± 10% power supply on all units.

Once the cause of the trip has been verified and remedied, the reclosing (RESET) can be done by turning the unit off and on at the thermostat / control switch or by restoring power through the sensitive loop.