Cleveland Convotherm OEB-20.20 Service And Parts Manual page 45

5 With the combi in the Hot Air mode with time on the timer, the door closed and the
start switch is depressed
a The front display will include a lighted bar under the Hot Air symbol
• When the heat circuit is energized the heat symbol will be energized
• The cooking mode symbol will be energized.
• The time display will invert and begin to count down.
b The fan circuit is energized
• NOTE: If the temperature is less than 212 degrees F than fan will be pulsed
on for 2 seconds every 60 seconds after the cabinet set temp (B6)
• If the combi fan is in the normal setting 220 VAC is sent from terminal 5 on
connector X11 through the normally closed auxiliary contacts of contactor
K57 to the coils of contactors K55 and K56
◊ The K55 and K56 contactors close sending 220 VAC through the Q56
overload to the motor and the motor turns at a high speed.
◊ The normally closed auxiliary contacts of both K55 and K56 open
preventing the K57 contactor from energizing.
• If the combi fan is in the reduced setting 220 VAC is sent from terminal 6 on
connector X11 through the normally closed auxiliary contacts of contactors
K55 and K56 to the coil of contactor K57
◊ The K57 contactor closes Sending 220 VAC through the Q57 thermal
overload to the motor and the motor turns at a reduced speed.
◊ The normally closed auxiliary contacts of K57 open preventing the K55
and K56 contactors from energizing.
• For the first 2 minutes 220 VAC is sent from terminal 4 on connector X11
through the normally closed auxiliary contacts of contactor K5 to the K50
contactor coil
◊ K50 contactor closes and the motor turns CW
◊ The normally closed auxiliary contacts on K50 open preventing the K5
contactor from energizing.
• For 15 seconds the motor is de-energized and allowed to coast.
• For the next 2 minutes 220 VAC is sent from terminal 3 on connector X11
through the normally closed auxiliary contacts of contactor K50 to the K5
contactor coil
◊ K5 contactor closes and the motor turns CCW
◊ The normally closed auxiliary contacts on K5 open preventing the K50
contactor from energizing.
• NOTE: If the door switch (S7) opens by the door opening, then the fan circuit
is de-energized. Then the motor will be pulsed in the opposite direction to
"break" the fan. This is to stop the fan quicker for the operator.
c The hot air heat circuit is energized
• 220 VAC is sent from terminal 3 of connector X12 on the Control Board
(A10) through the normally closed auxiliary contacts of K2 and K1 to the coil
of Contactor K4 until the cabinet reaches the set temperature.
◊ The contactor K4 closes and to legs of the 220 VAC is sent to the 18 KW
element (E4)