Hussmann Safe-NET III User Instructions

1

USER INSTRUCTIONS

Your refrigerated case uses a Hussmann Safe-NETTMIII temperature and
defrost controller to precisely maintain the temperature and prevent frost
buildup on the cooling coil. LEDs indicate when the compressor or
refrigeration is on, when the case is in a defrost cycle, if the temperature is
outside the desired range, or if there is a sensor failure. An adjustment knob
allows the temperature to be set within the configured range and can power
off the controller and compressor.Your controller has been custom-configured
to provide the best temperature and defrost control for your chilled or frozen
food.

The front of the controller has an adjustment knob and status LEDs. The back
of the controller has connections for sensors and switched equipment.

Temperature and
Defrost Controller

2

The Safe-NET III controller includes the following features and connections.

• Adjustment knob:
Adjusts the temperature setpoint.
May include an Off Position to turn off the controller, refrigeration, and
defrost heat and fan.
See Your Case Configuration on page 7.

WARNING: The optional evaporator fan remains ON when the

adjustment knob is in the Off position.

• Controller LEDs:

Compressor Powered On LED (green):
Lights while the compressor is running or the refrigeration valve
is open.

Defrost Cycle LED (yellow):
Lights while the refrigeration coil is defrosting.

Temperature or Sensor Alarm (red):
Lights if the temperature is too warm or too cold.
Flashes if a sensor fails.

See Alarms and Codes on page 7.

• Rear connections:
– Case temperature sensor:

Typically senses the temperature of the air in the case.
Used by the controller to determine when to power on or power off
the compressor or refrigeration.

– Evaporator temperature sensor:

Senses the temperature of the refrigeration coil.
Terminates a defrost cycle when refrigeration coil ice melts.

– Compressor or refrigeration relay:

Switches on the compressor or refrigeration valve for cooling.

– Defrost relay:

The Safe-NET III controller includes a defrost relay that switches on
the optional evaporator fan during normal operation and switches on
the defrost heater during a defrost cycle.

3

Display

The display includes three red LEDs and two digits for temperature, defrost
status, and error codes.

The three display LEDs are red, and their behavior matches the LEDs on the
controller.

Startup

1. Plug in the case.

WARNING: The Off Position does not disconnect line voltage to the case,

refrigeration unit, fan, or heater.

2. Wait for the self check to complete. During the self check, each LED
flashes for one second, then all LEDs turn on for two seconds. If the
LEDs do not flash, make sure the adjustment knob is not in the Off
position. (See Your Case Configuration on page 7 for Off position
functionality.)

• After the self check, all LEDs turn off until the compressor starts.

There may be a delay before the compressor starts.
If the red Temperature or Sensor Alarm LED stays on after the self
check, see Alarms and Codes on page 4.

• The green Compressor Powered On LED turns on when the

compressor starts.

Temperature Adjustment

Rotate the adjustment knob counter clockwise for a warmer setpoint or
clockwise for a colder setpoint.

• While you are adjusting the temperature, the optional display shows the
setpoint (cut out value). A few seconds after you set the temperature, it
reverts to showing the sensed temperature in the case.