Electrolux EW27MO55HSA, Technical & Service Manual

Page: 16 / 48

Operation
2-4
DOOR SENSING AND PRIMARY INTERLOCK SWITCH
The door sensing switch, in the third door switch system
is mounted on the right latch hook. The primary and
monitor interlock switch is mounted on the left latch hook.
They are activated by the latch heads on the door. When
the door is opened, the switches interrupt the circuit to
all components. A cook cycle cannot take place until the
door is firmly closed, thereby activating both interlock
switches. The third door switch system consists of the
door sensing switch and secondary interlock relay
located on the control circuit board.
AUTO DEFROST COOKING
The AUTO DEFROST key is a special function key to
defrost meats and poultry faster and better. AUTO DE-
FROST automatically defrosts roast beef, chicken etc..
When the AUTO DEFROST is selected and the food
weight is entered by using the AUTO DEFROST pad, the
oven will cook according to the special cooking sequence.
Figure 2-3. Door Sensing Switch, Monitor Switch,
Third Door Switch And Primary Interlock Switch
Component Descriptions
Monitor switch
Latch hook left
Latch
head
Primary
interlock switch
Door
sensing switch
Latch hook right
3rd door switch
Door handle
Latch
head
MONITOR SWITCH
The monitor switch is mounted on the middle position of
latch hook. It is activated (the contacts opened) by the
lower latch head while the door is closed. The switch
is intended to render the oven inoperative by means of
blowing the monitor fuse when the contacts of the relay
RY1 and primary interlock switch fail to open when the
door is opened.
Functions:
1. When the door is opened, the monitor switch
contacts close (to the ON condition) due to their
being normally closed. At this time, the door sensing
and primary interlock and third door switches are in
the OFF condition (contacts open) due to their being
normally open contact switches.
2. As the door goes to a closed position, the monitor
switch contacts are first opened and then the door
sensing switch, third door switch and the primary
interlock switch contacts close. (On opening the door,
each of these switches operate inversely.)
3. If the door is opened, and the relay RY1 and the
primary interlock switch contacts fail to open, the
monitor fuse blows simultaneously with closing of the
monitor switch contacts.
THIRD DOOR SWITCH
The switch is activated by the latch heads, while the door
is closed. When the door is opened, the switch interrupts
the circuit to the power transformer. This switch prevents
power transformer engaging and microwave when the
door opened.
Before replacing a blown monitor fuse, test the door
sensing switch, primary interlock switch, Relay (RY1)
and monitor switch for proper operation.
Monitor fuse and switch are replaced as an assembly.