Ignition Control Module for Modulating Gas Furnace (240 MBH Furnace Only)
Figure 29: Typical Modulating Gas Furnace Electrical Schematic with Sensor
Variable Furnace Controller
Daikin's furnace controller is an electronic device that delivers
full control of the modulating furnace. Control includes
sequencing, ignition, safety, modulation of the control valve,
and the induced draft motor. Inputs to the furnace control board
are an a 0-10V signal. The analog signal will modulate the
burner down to 25% of full load. Safety inputs include pressure
line and electrical connection from the airflow proofing switch
and electrical connection from the rollout switches. Control
board outputs are to the igniter board, modulating gas valve,
and to the induce draft motor.
Ignition Control Module LED
Diagnostics
The LED indicators (
) can be used to diagnose faults
associated with the modulating gas furnace.
Table 20: LED Indicator and Fault Conditions
Indicator
Fault Condition
Steady Off
No power or control hardware fault Indicator Fault
Condition
Steady On
Control fault detected or no 24 VAC power
1 Flash
Combustion fan motor energized, pressure switch open
2 Flashes
Inducer air pressure reads above zero level when the
inducer is off
3 Flashes
Flame is on when is should be off or flame is off when it
should be on
4 Flashes
Gas valve is on when is should be off or gas valve is off
when it should be on
5 Flashes
Safety relay is on when it should be off or safety relay is off
when it should be on
6 Flashes
Excessive plenum temperature
7 Flashes
High limit switch is open or fuse is open
8 Flashes
Pressure switch failed to operate or modulation current is
incorrect
Slow Flash
Normal operation - no call for heat
1 Slow
Flash Call for heat
2 Slow
Flashes Gas on - call for heat
3 Slow
Flashes Gas on - no call for heat
Rapid Flash
Retry
40VA
24VAC
115VAC
Neutral
Ground
120VAC
T1
T3
T6
T9
T7
T5
T4
T2
M
Neutral
Hot
Hot
Neutral
Variable
Inducer
Inducer
HS
I
Flame
Flame Sensor
24V
AC
115
VAC
Spark Electrode
W
R
+
-
J4
J8
+
-
J9
J3
ROS1
APS
ROS2
Sensing hose
to fan
-
+
Pressure
Transducer
J5
Modulating
Gas Valve
24VAC
GND
MOD
RTN
MOD
MV
RTN
MV
Combustion
Board
Limi
t
Pr
es
s
Switch
DSI
Board
L1
L2
0-10VDC
0-10V
DC
input si
gnal
Comm
Po
rt
MJ
Status
LED
WHT
BLK
WHT
BLU
RED
WHT
GRY
ORG
ORG
WH
T
BL
K
WHT
WHT
BLK
WHT
BLK
GRN
WHT
BLK
Gn
d
GRY
RED
BLU
BRN
RED
1/4" Quick Connect Terminal
Terminal Block
APS
Airflow Proving Switch
ROS1
Roll Out Switch #1
ROS2
Roll Out Switch #2
o
PTIonal
G
as
h
eaT
www.DaikinApplied.com
35
IM 1058-8 • MAVERICK II ROOFTOP SYSTEMS