Heatcraft Refrigeration Products H-IM-79B Error Indicator

At initial power up, each Beacon board checks for system errors. The system error check

involves checking the various temperature sensors to determine whether any of these

sensors are shorted or open.

The system will pumpdown and cycle off and will not restart until the fault is cleared or

the circuit breaker reset, for the following conditions:

- Suction sensor shorted, open or not installed

- Room temperature sensor shorted or not installed

- Pressure Transducer open or not installed

The system will pumpdown, cycle off and try to restart for three consecutive times. Each

try will be after the 4 minutes “Hold Off” period, for the following fault conditions:

- Superheat too low

- High pressure or low pressure cutout

- Oil pressure

After the third try, the system will shut down and not try to restart. The Alarm contacts will

be closed and an alarm message displayed on the LED.

- Room temperature sensor shorted, open or not installed

- Defrost temperature sensor shorted, open or not installed

- Suction temperature sensor shorted, open or not installed

- Suction pressure transducer shorted, open or not installed

- Outdoor temperature sensor shorted

- Low superheat

- Compressor shut down (high or low pressure switch open or oil pressure

switch open)

- Multi-in/multi-out wiring error

In some installations, it is desirable to shut off the evaporator fans periodically. This is easily

accomplished on Beacon II by wiring a single pole, single throw switch (SPST) between the

terminals marked “SERVICE” and “COM” on the Beacon II board. Closing this switch will

cause the system to pumpdown and shut off. Air Defrost fan motors must be wired through

the fan relay on the Beacon II board for this to be effective on Air Defrost systems. The

entire system will be shut off and remain off until the SPST switch is opened.

Air Defrost evaporator fans are setup to run constantly. If there is a need to shut down the

evaporator fans on an Air Defrost system, this can be accomplished by wiring the

evaporator fan motor or evaporator fan motor contactor through the fan relay on the

Beacon II board. When this is done and the Air Defrost system is placed in “SERVICE,” the

evaporator fans will shut off when the system is in pumpdown.

Error Indicator