Testing Inducer Motor - Daikin APGM3 Service And Troubleshooting

SERVICING
If the rollout control has opened, the circuit between the
ignition control and gas valve will be interrupted and the
ignition control module will go into lockout. The servicer
should reset the ignition control by opening and closing the
thermostat circuit. The servicer should look for the ignitor
sparking which indicates there is power to the ignition
control. The servicer should measure the voltage between
each side of the rollout control and ground while the ignition
control is try to power the gas valve.
Checking Flame Rollout Switch
Limit Switch Operation (Applies to Primary,
Auxiliary, and Roll Out Limits) DSI systems.
If a limit switch opens, the indoor blower is energized on
heat speed and the induced draft blower is energized. The
LED on the control flashes "4" to indicate an open limit
switch. The blower and inducer remain on while the limit
switch is open. The gas valve is de-energized. Power to the
thermostat "R" is removed while the limit switch is open.
When the limit switch re-closes, the induced draft motor
runs through its post purge and the indoor blower goes
through the heat off delay.
If a call for heat exists when the limit switch re-closes, the
control goes through a pre-purge period and then makes
an ignition attempt. The indoor blower remains on (for the
delay off time) during the re-ignition attempt.
1. If no voltage is measured on either side of control it
indicates ignition control or wiring to control problem.
2. If voltage is measured on one side of the control and
not the other, it indicates the control is open.
3. If voltage is measured on both sides of the control the
wiring to gas valve or valve is at fault.
Servicing procedure with furnace not firing.
1. Confirm that the outer door was in place and all
screws tightened. (No leaks under the door.)
2. Check to see if any damage was done to the furnace
especially the wiring.
3. Confirm that heat exchanger is not obstructed by
feeling for discharge air from the flue hood when the
combustion blower is running but the unit is not firing.
If the above steps do not suggest the reason the control
has tripped the furnace should be fired.
1. Remove the heating compartment door.
2. Turn of the power or open the thermostat circuit.
3. Reset the rollout control.
4. Turn power on and put the unit into a call for heating.
Flame rollout could occur. Keep face and hands a safe
distance from burner area.
5. Look under the heat shield as the unit is running.
Flames should be drawn into firing tubes.
a. If only one burners flame is not drawn into the
tube, that tube is restricted.
b. If, without the air circulation blower running, all
flames are not drawn into the tubes either the
collector box, combustion blower, or flue outlet
is obstructed. If the combustion blower or flue
outlet is obstructed, the pressure switch should
have opened preventing the unit from firing, also
inspect the unit pressure switch and wiring.
c. If the burner flame is not drawn into the tube only
when the air circulation blower is running, then a
cracked heat exchanger tube is present.

Testing Inducer Motor

High Voltage!
Disconnect all power before servicing or
installing. Multiple power sources may be
present. Failure to do so may cause property
damage, personal injury or death.
1. Disconnect the motor wire leads from its connection
point at integrated ignition control module.
2. Using and ohmmeter, test for continuity between each
of the motor leads.
3. Touch one probe of the ohmmeter to the motor frame
(ground) and the other probe in turn to each lead.
CAUTION
WARNING
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