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SERVICING
40
Testing Direct Spark Ignition (DSI) systems
Thermostat calling for heat (15 second pre-purge time and
7 second trial for ignition).
1. Check for 230 VAC from L1 terminal of control module
to L2. No voltage - check wire connections, continuity,
etc.
2. Check for 24 VAC at “R” to “C” thermostat terminals.
a. No voltage - check 3 amp automotive type fuse
on control board. A blown fuse would indicate a
short in the 24 VAC circuit (thermostat or limit
circuit).
b. Voltage Present - check limit, auxiliary limit
and rollout. If limit, auxiliary limit and rollout are
closed, then check for 24 VAC at the gas valve
terminals.
No 24 VAC at gas valve - replace Control board.
Status Light Equipment Status
Check
On
Normal Operation
Off
No Power or
Internal Control Fault
Check Input Power,
Check Fuse on Control,
Replace Control
1 Blink
Ignition Failure,
Open Rollout Switch,
or Open Aux. Limit
Switch
Check Gas Flow,
Check Gas Pressure,
Check Gas Valve,
Check Flame Sensor,
Check Flame Rollout,
Check Aux. Limit.
2 Blinks
Pressure Switch
Open
Check Pressure Switch
3 Blinks
Pressure Switch
Closed
Check Pressure Switch
4 Blinks
Open Main Limit
Switch
Main Limit Switch Open
5 Blinks
False Flame Sensed
Sticking Gas Valve
6 Blinks
Compressor Output
Delay
3 Minute Compressor
Anti-Cycle Timer
PCBAG123 Ignition Board Fault Codes
NOTE: The flash rate is 0.25 seconds on, 0.25 seconds
off, with a 2-second pause between codes.
3
2
1
6
5
4
9
8
7
12
11
10
L2
L2
L2
L2
COOL
HEAT
UNUSED
L1
L1
D1
FS
Diag
no
st
ic L
ED
Blower Off Delay Settings
Transformer
speed up
PCBAG123 DSI Control Board
Testing Direct Spark Ignition (DSI) Systems
PCBAG127 Board
Heating Mode
Indoor thermostat calling for heat (15 second pre-purge
time and 7 second trial for ignition).
1. Check for 230 volts from L1 terminal of control module
to L2. No voltage - check wire connections, continuity,
etc.
2. Check for 24 volts at “R” to “C” thermostat terminals.
a. No voltage - check 3 amp automotive type fuse
on control board. A blown fuse could indicate
a short in the 24 volt circuit (thermostat or limit
circuit).
b. Voltage Present - check limit and rollout. If limit
and rollout are closed, then check for 24 VAC at
the gas valve terminals.
c. No 24 VAC at gas valve - check 9 pin connector
and wires from ignition control to gas valve. If
wires and connections at 9 pin connector check
good, replace ignition control.
d. Voltage present at gas valve - replace gas valve.