Daikin DM92SE, Service Instructions Manual, Page: 44 / 57

44
SERVICING
Cooling Anticipator
The cooling anticipator is a small heater (resistor) in the
thermostat. During the "OFF" cycle it heats the bimetal
element helping the thermostat call for the next cooling
cycle. This prevents the room temperature from rising
too high before the system is restarted. A properly sized
anticipator should maintain room temperature within 1 1/2
to 2 degrees.
The anticipator is fixed in the subbase and is not to be replaced.
If the anticipator should fail for any reason, the subbase must
be changed.
S-4 CHECKING TRANSFORMER AND
CONTROL CIRCUIT
A step-down transformer 120 volt primary to 24 volt secondary,
40 VA (Heating and Cooling Models) supplies ample capacity
of power for either operation.
WARNING
HIGH VOLTAGE
D
ISCONNECT
ALL
POWER BEFORE SERVICING OR
CHANGING ANY ELECTRICAL WIRING.
M
ULTIPLE POWER
SOURCES MAY BE PRESENT.
F
AILURE TO DO SO MAY CAUSE
PROPERTY DAMAGE, PERSONAL INJURY OR DEATH.
1.
Remove blower compartment door to gain access to
the thermostat low voltage wires located at the furnace
integrated control module.
2. Remove the thermostat low voltage wires at the furnace
integrated control module terminals.
With Power On (and Door Interlock Switch closed):
L
INE VOLTAGE NOW PRESENT
WARNING
3. Use a voltmeter, check voltage across terminals R and C.
Must read 24 VAC.
4. No voltage indicates faulty transformer, open fuse, bad
wiring, bad splice, or open door interlock switch.
5. Check transformer primary voltage at incoming line voltage
connections, fuse, splices, and blower door interlock
switch.
6. If line voltage is available to the primary side of transformer
and not at secondary side, the transformer is inoperative.
Replace.
7. After completing check and/or replacement of transformer
and check and/or repair of control circuit, reinstall blower
compartment door.
8. Turn on electrical power and verify proper unit operation.
S-16A CHECKING AIR CIRCULATOR BLOWER
BLOWER MOTOR
D
ISCONNECT
ALL
POWER BEFORE SERVICING.
WARNING
1. Remove blower compartment door to gain access to the
circulator blower motor and integrated ignition control.
2. Check for any obstruction that would keep the fan wheel
/ fan motor from turning.
3. Check wiring, the motor has two wiring harnesses, a main
harness and a control harness. The main pin harness has:
White neutral wire connected to the Neutral terminal on
the control board.
Black wire connected to the CIRC H terminal on the control
board.
Red wire connected to the COM terminal, which is a female
spade connection next to the T1 – T4 wires on the control
board.
Green ground wire connected to cabinet ground
The control harness has:
Blue wire connected to T1 on the control board.
Red wire connected to T2 on the control board.
Orange wire connected to T3 on the control board.
Black wire connected to T4 on the control board.
The multi-speed ECM motor requires a line voltage power
supply (black connected to CIRC H and white connected
to neutral on the control board) as well as a signal on one
of the speed taps (T1-T4).
The speed tap voltage is A.C. and can vary which tap is
energized depending on DIP switch selection. The volt-
age reading from any one of the speed taps is referenced
between the female COM terminal next to the speed taps
on the control board. From COM to T1 or T2, T3, T4,
you should read 24 VAC on the low voltage speed taps
depending on Dip switch settings.
.
Motor Tap Identification
CONNECTOR ID DESCRIPTION CONNECTOR VOLTAGE
L LINE, L1 LINE, L1
G GROUND CHASSIS GROUND
N LINE, L2 LINE, L2
C SIGNAL COMMON 24VAC COMMON
1 TAP 1 24VAC
2 TAP 2 24VAC
3 TAP 3 24VAC
4 TAP 4 24VAC
5 TAP 5 24VAC