Manual Emergency Mode Operation

In the event of an emergency situation where a fatal failure of the controller occurs, a manual emergency mode function can be used to operate the unit. Manual control offers a selection of three fixed operating functions:

  • Cooling (frozen): Both compressors, the condenser fan and the evaporator fans operate continuously. The liquid line solenoid is energized with the R-134a compressor.

  • Defrost: Heaters are activated for defrost (evaporator fans off).

  • Evap Fan: Evaporator fans are activated.

    Caution
  • Service procedure
  • The unit must be cycled manually to maintain the desired temperature. Monitor container temperature with an external thermometer.

To select Manual Control:

  1. Turn the Unit On/Off switch to OFF.

  2. Disconnect the unit power cord from the power supply.

      Warning
    • Risk of Injury!
    • High voltage (460/380 volts) is present on the contactors and relays in the control box. To prevent dangerous electrical shock, disconnect the supply power to the unit whenever possible when working in this area.

  3. Disconnect cable no. 2 from the controller and main relay board (see electrical schematic).

  4. Disconnect the 2-pin plug from J501 (see decal on main relay board). Re-locate plug according to the function required: Defrost or Cool.

  5. Connect the unit power cord to the proper power supply.

  6. Turn the Unit On/Off switch to ON. Unit will start and operate.

  7. Check for correct rotation of condenser fan and evaporator fans. Condenser air should be blowing out from the center of the grille. Evaporator air should be blowing down through the evaporator coil. If the fans are running backwards, the power supply phase must be changed.

Manual Emergency Control Connections

Parent topic: Microprcessor Controller