Operations Manual

9
MASTER-BILT ELECTRONIC REFRIGERATION CONTROL
OPERATION
Compressor When power is first turned on to the control, the LED indicator under COMP on the
display starts blinking. After one-minute delay the compressor comes on. The COMP LED indicator
stays on while compressor relay is energized. Display will show actual box temperature. Figure 4 is
the display layout.
The compressor will be cycled off when the actual box temperature reaches its set point. The
COMP indicator will be off.
Fig. 4 – Display Lay-out
Fan The fans will run constantly except when a defrost is initiated, or when the evaporator temp
is above the 30
o
F. When in defrost mode the fan is off until the end of the defrost and the 2 minute
drip time has passed. There is 4 minutes delay after a defrost before the fan comes on. The
difference of the evaporator and room temperature of more than 9
o
F will override the fan delay. FAN
LED indicator is on while FAN relay is energized.
Defrost The control uses time defrost with 4 defrost per day. A programmed “HOT-KEY” has
to be used to re-set the defrost scheme for special applications. During defrost the display will show
dEF and the LED indicator under DEF in on. The control begins timing the defrost when power is
turned on. Four defrost per day means it will occur every 6 hours. To have defrost occur at 8am,
2pm, 8pm, and 2am then power up at one of these four times.
MANUAL DEFROST
1. Push this DEFROST
key for more than 2 seconds and a manual defrost will start.
2. While in defrost, Push and hold the DEFROST
key for more than 5 seconds and
the controller will end the defrost cycle. The controller will then enter drip mode for 2
minutes. The DEF led is flashing in drip mode.
HOW TO SEE THE SETPOINT (Box temperature cut-out)
1.
Push and immediately release the SET key: the display will show the Set
point value;
2. Push and immediately release the SET key or wait for 5 seconds to display the probe value
(actual box temperature) again.