Thermostat Operation (Electric Model) - Fisher & Paykel DE09 Service Manual

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5.3.4

Thermostat Operation (Electric Model)

There are three thermostats that control the temperature of the dryer and a hi-limit thermostat that
will shut the dryer down if it overheats.
The hi-limit thermostat is mounted on the heater cowl and is in circuit with the motor. If it shuts
down, the motor stops. There is a switch on the motor, which cut the neutral to the element when
the motor stops, so when the hi-limit trips, all dryer functions cease to operate.
The heating elements are controlled by the safety, inlet and outlet thermostats.
When the selector is set on No Heat/Fluff, no power is supplied from terminal 16 so there is no
element operation.
When the selector is set on Normal Heat/Cotton Regular, power is supplied only through the direct
element circuit (as shown in Section 5.3.3). Temperature is controlled by the safety thermostat,
which is located on the heater cowl.
When the selector is set on Med Heat/ Permanent Press, power runs through two circuits. Power
is supplied off terminal 16 to the element circuit. Power is also switched onto the control circuit for
control inlet thermostat. The control circuit for the control inlet thermostat has an active supply
from the L1 circuit for the element. The neutral of the control circuit is switched between terminals
8 and 7 (terminal 7 is the common neutral connection on the selector switch). The thermostat will
not operate unless there is power through the resistor in the thermostat. The resistor has a
resistance of 9 Kohms. This thermostat only switches one element.
When the selector is set on Low Heat/Knits Delicates, the element circuit and the control circuits
for the inlet and exhaust thermostats is used. Terminal 7 on the selector is the common neutral
connection and the exhaust thermostat is switched to it on terminal 6. The active supply for the
exhaust thermostat control is from the L2 line. The resistor has a resistance of 9 Kohms.
See the diagrams on the next page.
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