The Heating Circuit; Drying Time; Electrical Operation (Gas Dryers Models) - Frigidaire 27" Dryers with electronic controls Service Manual

It compares the reading from the thermistor to the tem-
perature setting for the cycle.

The Heating Circuit:

The electronic control board applies power to the heat-
ing circuit through the contacts of heater relay RL 2.
When the electronic control senses the temperature in
the drum is below the programmed temperature, it closes
the contact of RL 2. This applies line 1 power to the
high limit thermostat that is mounted on the heating el-
ement assembly.
The high limit thermostat is a safety device that prevents
the dryer from overheating if the contacts of the RL 2 fail
closed. The contacts of the high limit thermostat are
normally closed and are set to open at a temperature
above the preset temperature specifications of the elec-
tronic control board. From the output terminal of the
high limit thermostat, line 1 is connected to one side of
the element. The other side of the heating element is
connected to line 2 through the contacts of the second
centrifugal switch in the drive motor. This switch pre-
vents power from being applied to the element if the motor
is not running.

Drying Time:

The amount of drying time is determined in one of two
ways. A fixed amount of drying time may be set by
touching the TIMED DRY pad. The AUTO DRY cycles
that variable amount of time by the size of the load, the
amount of moisture in the clothes and the dryness set-
ting selected.
Pressing TIME DRY will select 45 minutes of drying time.
The time will increase 5 minutes each time TIME DRY is
pressed. The maximum drying time is approximately
110 minutes. If you desire less than 45 minutes, you
must advance beyond the 110 minute mark to start again
at 15 minutes.
In the AUTO DRY cycles the electronic control reads
the capacitance between the two sensor bars located in
the vent cover.
When wet clothes are placed in the dryer, the clothes
touch the sensor bars and the moisture lowers the ca-
pacitance between the bars. As the dryer runs, mois-
ture is removed from the clothes, the capacitance be-
tween the bars increases. When the increase in ca-
pacitance satisfies the electronic control, the cycle sta-
tus will change from "Auto Dry" to "Cool Down" and
the load is tumbled without heat. At the end of cycle
"dn" is displayed and the electronic control will turn the
dryer off.

Electrical Operation (Gas Dryers Models)

Note: Always refer to the wiring diagram or sche-
matic with the product.
Sample wiring diagram.
120 VAC 60 HZ
L1
RED
J11
RED
CONTACT
SENSOR
ELECTRONIC
CONTROL
RED
RED/WHT
BOARD
J12
GRN
BLUE
CABINET
J14-3
CONTROL
50K OHMS
THERMISTOR
BLUE
NOTE
J14-4
DASHED LINES INDICATE
CIRCUITS THAT ARE NOT
IN ALL MODELS
RED
NC
COM
RL 1
ORANGE
NO
TAN
J13
MOTOR
DOOR
SWITCH RELAY
RL 2
RED
HEATER
COM
RELAY
When the dryer is connected to electrical power, line 1
is connected to the terminal marked COM on the door
switch and the COM. terminal of the heater relay that is
mounted on the electronic control board. The COM.
terminal of the heater relay provides power to the com-
mon contact of the relay and also provides power to the
electronic control board. The electronic control board
44
CABINET
WHITE
J14-1
WHITE
BLACK
WHITE
DRUM LIGHT
M5
START
M4
GRAY
J9
RUN
MOTOR
FLAME
IGNITER
SENSOR
WHT
ORG WHT WHT
ORG
5
3 1
4
WHT
SECONDARY BOOSTER
ORG
ORG COIL COIL
ORG HOLDING
NO 2
HIGH LIMIT GAS VALVE COIL
THERMOSTAT ASSEMBLY
N
WHITE
WHITE
M1
GRN
M2
CABINET
YEL
BASE