Frigidaire GLBM188HB, Service Manual

Page: 13 / 47

Page 13
GLBM188HB
6 – 4
[3] DESCRIPTION AND FUNCTION OF COMPONENTS
1. DOOR OPEN MECHANISM
The door is opened by pulling the door handle, refer to the Figure D-1.
Figure D-1. Door Open Mechanism.
2. DOOR SENSING SWITCH, SECONDARY INTER-
LOCK SWITCH
The secondary interlock switch is mounted in the lower position of the
latch hook, the door sensing switch in the primary interlock system is
mounted in the upper position of the latch hook is mounted on upper
position of the 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 primary interlock
system consists of the door sensing switch and primary interlock relay
located on the control circuit board.
3. MONITOR SWITCH
The monitor switch is activated (the contacts opened) by the latch
head on the door 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 primary interlock relay (RY2) and secondary
interlock switch fail to open when the door is opened.
Functions:
1. When the door is opened, the monitor switch contact close (to the
ON condition) due to their being normally closed. At this time the
primary interlock relay (RY2), secondary interlock switch are in the
OFF condition (contacts open) due to their being normally open
contact switches. And the contacts of relay (RY1) are in the ON
condition (contacts close).
2. As the door goes to a closed position, the monitor switch contacts
are first opened and then the door sensing switch and the second-
ary interlock switch contacts close. (On opening the door, each of
these switches operate inversely.)
3. If the door is opened, and the primary interlock relay (RY2) and
secondary interlock switch contacts fail to open, the monitor fuse
blows simultaneously with closing of the monitor switch contacts.
CAUTION: BEFORE REPLACING A BLOWN MONITOR FUSE TEST
THE DOOR SENSING SWITCH, PRIMARY INTERLOCK
RELAY (RY2), RELAY (RY1), SECONDARY INTERLOCK
SWITCH AND MONITOR SWITCH FOR PROPER OPER-
ATION. (REFER TO CHAPTER “TEST PROCEDURE”).
NOTE: MONITOR FUSE AND MONITOR SWITCH ARE REPLACED
AS AN ASSEMBLY.
4. THERMAL CUT-OUT (CAVITY)
This thermal cut-out is located on the top of the oven cavity. It is
designed to prevent damage to the oven unit if the food in the oven
catches fire due to overheating produced by improper setting of cook-
ing time or failure of control unit. Under normal operation, the thermal
cut-out remains closed. However, the thermal cut-out will open at
293 ° F (145 ° C) causing the oven to shut down.
5. TURNTABLE MOTOR
The turntable motor rotates the turntable located on the bottom of the
oven cavity, so that the foods on the turntable cook evenly during
cooking. Turntable will turn in either direction. The turntable motor can
be turned off by touching TURNTABLE ON/OFF pad.
6. COOLING FAN MOTOR
The cooling fan motor drives a blade which draws external cool air.
This cool air is directed through the air vanes surrounding the magne-
tron and cools the magnetron. This air is channelled through the oven
cavity to remove steam and vapors given off from the heating foods. It
is then exhausted through the exhausting air vents at the oven cavity.
7. HOOD FAN MOTOR
The hood fan motor is a two-speed, single-phase, double pole induc-
tion type, requiring a hood fan capacitor. It is located outside the upper
rear part of the oven cavity, is to remove, from around the oven, hot air
rising from the conventional electric or gas range over which it is
installed. This air is then expelled either vertically or horizontally
through the customer supplied duct system, or discharged back into
the kitchen. The automatically operation is medium speed. The man-
ual operation is a three speed (Low/ High).
7.1. THERMOSTAT (60 ° C ON)
This thermostat is located on the right base plate. It is designed to
automatically turn on the hood fan motor whenever the hot air rising
from the conventional range below causes the temperature at the ther-
mostat to rise to 140 ° F (60 ° C) or higher, thus removing this hot air
from around microwave oven. When the temperature around the ther-
mostat drops to 113 ° F (45 ° C) or lower, the thermostat shuts off the
hood fan motor.
8. ANTENNA MOTOR
The motor drives the stirrer fan to stir the microwave radiation from the
waveguide.
9. COOK TOP LAMP
The cook top lamp is mounted at the lamp mounting angle on the base
cover. Touch the Light pad once for high, twice for low and four times
to turn off the light.
Secondary
Interlock
Switch
Monitor
Switch
Latch
Hook
Door
Latch
Heads
Door
Sensing
Switch