KitchenAid KHMS105E - Blower Motor Control Logic

1-2
The normally-closed (N.C.) contacts of relay 4 provide a potential circuit for the Base Thermal
Fuse (see the following strip circuit). If the base of the oven exceeds 133˚F, the thermal fuse
contacts close, and a circuit for the low-speed side of the blower motor is completed, which turns
the motor on. The low-speed blower will operate until the base temperature drops below 104˚F
and opens the thermal fuse contacts, and turns off.
N
L1
15A LINE
FUSE
CAVITY
THERMAL
FUSE
MAGNETRON
THERMAL
FUSE
BK
BK
BK
BK
RELAY #4
BASE
THERMAL
FUSE
W
BL
YL
LOW-VOLTAGE
TRANSFORMER
W
BLOWER
MOTOR
LOW
RD
MICROCOMPUTER
BOARD
4 1
7
CAPACITOR
Y
R
When the low-speed fan is selected by the user at the control panel, relay 3 and the normally-
closed (N.C.) contacts of relay 4, complete the circuit to the low-speed windings of the blower
motor and turn it on.
N
L1
15A LINE
FUSE
CAVITY
THERMAL
FUSE
MAGNETRON
THERMAL
FUSE
BK
BK
BK
BK
RELAY #4
W
BL
BR
LOW-VOLTAGE
TRANSFORMER
W
BLOWER
MOTOR
LOW
RD
RELAY #3
MICROCOMPUTER
BOARD
4 1
6
CAPACITOR
Y
R
When the high-speed fan is selected by the user at the control panel, the normally-open (N.O.)
contacts of relay 4 complete the circuit to the high-speed windings of the blower motor and turn
it on.
N
L1
15A LINE
FUSE
CAVITY
THERMAL
FUSE
MAGNETRON
THERMAL
FUSE
BK
BK
BK
BK
RELAY #4
W
BL
BK
LOW-VOLTAGE
TRANSFORMER
BLOWER
MOTOR
HIGH
RD
MICROCOMPUTER
BOARD
4 1
8
CAPACITOR
Y
R