Service Manual

13
B. Sequence of Operation
1. Sequence Cycles and Shutdown
The steps in the sequence are as outlined below. When power is supplied, CB red
"POWEROK"LEDandCBgreen"BCCLOSED"LEDturnson.IfCByellow"BCOPEN"
LED is on, the unit will not start. In this case, clear ice away from the BC actuator paddle
in the dispenser unit/storage bin area. A 5-second delay occurs at startup. Note that the
order of the green sequence LEDs from the outer edge of CB is 1,4, 3, 2.
a) 1-Minute Fill Cycle
LED 4 is on. WV and X11 relay energize. After 1 minute, CB checks for a closed F/S. If
F/S is closed, the harvest cycle begins. If open, WV remains energized through additional
1-minute ll cycles until water lls the water tank and closes F/S. This serves as a low
water safety to protect PM.
b) Initial Harvest Cycle
LEDs 1, 4, and 2 are on. WV and X11 relay remain energized, Comp, FMR, HGVs, and
X10 relay energize. CBmonitors the warming of the evaporator via the thermistor located
on the suction line. When the thermistor reaches 48°F (9°C), CB reads a 3.9kΩ signal
from the thermistor and turns harvest termination over to the harvest timer. For details,
see"II.C.3.b)HarvestTimer(S4dipswitch1&2)."Thepump-outtimer(S4dipswitch
3 & 4) acts in place of the harvest timer during cycles with a pump-out. For details, see
"II.C.3.c)Pump-OutTimer(S4dipswitch3&4).WVandX11relayareenergizedduring
harvest for a maximum of 6 minutes or the length of harvest minus 50 seconds (harvest
pump timer (S4 dip switch 7)), whichever is shorter. 50 seconds before the harvest timer
terminates, LED 4 turns off, WV and X11 relay de-energize.
Harvest Pump Timer: LEDs 1,3, and 2 are on. LED3turns on and PM energizes.
Fordetails,see"II.C.3.e)HarvestPumpTimer(S4dipswitch7)." NOTICE! S4 dip
switch 7must remain in the factory default position of 7 on. Otherwise, PM will not
energize during the last 50 seconds of harvest. When the harvest timer terminates,
the harvest cycle is complete. CB checks the position of F/S and proceeds to the next
cycle if it is closed, or calls for a 1-minute ll cycle if it is open. The minimum total time
allowed by CB for a complete harvest cycle is 2 minutes.
c) Freeze Cycle
LED 1 is on. Comp, FMR, and PM remain energized. LLVs energize, HGVs and
X10relay de-energize. CB 5-minute short cycle protection timer prevents CB from
monitoring F/S for the rst 5 minutes of freeze. After the 5-minute short cycle protection
timer terminates, CB turns freeze termination over to F/S. As ice builds on the evaporator,
the water level in the water tank lowers. The freeze cycle continues until F/S opens. There
is a 15 second delay before CB acknowledges an open F/S and terminates the freeze
cycle.