Thermo Pride Gas/Propane Furnace Induced Draft Highboy/Counterflow/Horizontal MHA1 - Manual (Page 51)

All installations and services must be performed by qualified service personnel.
48
Is LED light on ignition
control module flashing?
Check all wiring for
loose connections.
No
Troubleshooting Complete.
Yes
Does the circulating air
blower turn off after
thermostat is satisfied
within 180 seconds?
Yes
Yes
Does burner shut off
when thermostat is
satisfied?
Check DIP switch settings
on ignition control module
against those on connection
diagram. Reset if necessary.
No
Check for short in wire to
thermostat. Replace
thermostat if necessary.
No
Yes
No
Yes
Does system run until
thermostat is satisfied?
If LED Light Flashes:
1 Flash, then pause............System lockout
2 Flashes, then pause........Pressure switch stuck closed
3 Flashes, then pause........Pressure switch stuck open
4 Flashes, then pause........Open high limit, aux. limit, or roll-out switch
6 Flashes, then pause........115 Volt AC power reversed
7 Flashes, then pause........Low flame sense signal
8 Flashes, then pause........Check ignitor or improper grounding
Continuous flashing............Flame has been sensed when no flame
(no pause) should be present (no call for heat)