Thermo King Corporation

James M Roush

Jay L Hanson

Doyle G Herrig

James E Nixon

Stanley O Hoium

Methods and apparatus for monitoring conditions which may cause shut down of a refrigeration unit. When a condition of the refrigeration unit is detected which requires shut down, a shut down counter is incremented and the shut down is made with the provision for automatic restart of the refrigeration unit in response to predetermined parameters of the refrigeration unit. When the predetermined parameters initiate automatic re-start of the refrigeration unit, a timer is started. If the refrigeration unit operates for a predetermined period of time without shut down, the counting means is reset. A shut down before expiration of the predetermined timing period again increments the shut down counter. In one embodiment, when a predetermined condition which may cause shut down approaches a predetermined shut down value, the methods and apparatus modify the operation of the refrigeration unit one or more times in an attempt to prevent shut down. A predetermined count value on the shut down counter prevents further automatic re-starts of the refrigeration unit. In a preferred embodiment, the monitored conditions which may cause shut down are the high side pressure of the refrigeration unit, and, when a refrigerant compressor is driven by an internal combustion engine, the temperature of the engine.

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Eagan, MN, United States of America

James M Roush