Methods of operating a refrigeration system

A method of detecting slippage of a clutch disposed between an internal combustion engine and a refrigerant compressor in a refrigeration system in which a prime mover for the compressor is selectable between the internal combustion engine and clutch, and an electric drive motor, and wherein the refrigeration system further includes an alternator driven by rotation of the compressor, and a battery connected to be charged by the alternator, comprising the steps of:

• detecting a predetermined fluctuation in the speed of the internal combustion engine, when the internal combustion engine is the selected prime mover,
• monitoring the polarity of the battery current, with a first polarity indicating battery charging current, and a second polarity indicating battery discharging current,
• and shutting the internal combustion engine down in response to:
• (1) the detecting step detecting said predetermined fluctuation in engine speed, and (2) the monitoring step detecting the second polarity.

A method of detecting reverse operation of an evaporator fan motor in a refrigeration system having a refrigerant compressor driven by a prime mover, with the evaporator fan motor driving air mover means which draws return air from a conditioned space and discharges conditioned air into the conditioned space, including the steps of:

• detecting the temperatures RA and DA of the return air and the discharge air, respectively,
• determining the difference between the temperatures RA and DA to provide a first difference value .DELTA.D,
• comparing said first difference value .DELTA.D with a first reference value,
• initiating a predetermined timing period when said first difference value .DELTA.D exceeds said first reference value,
• repeating, periodically, the steps of detecting the temperatures RA and DA of the return air and the discharge air, and the step of determining the difference between the temperatures RA and DA, to provide updated difference values .DELTA.D,
• comparing each of said updated difference values--.DELTA.D with a second reference value,
• and shutting the prime mover and fan motor down when the step of comparing each updated difference value .DELTA.D with the second reference value consistently finds that each updated difference value .DELTA.D exceeds said second reference value over said predetermined timing period.