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may be defective. Replace the gas valve if
necessary.
e. Be sure the pilot shield is in place.
f. Check for gas leaks in the pilot line or the pilot
assembly.
g. Check the flue assembly to make sure all
connections are tight.
h. See the FURNACE START-UP procedure
for lighting details.
Main Flame Is Not Burning Properly
a. Check the manifold gas pressure.
b. Check for the correct main burner orifice.
- See the nameplate SPECIFICATION.
Control Module Status Indicators - M1M Series
Control Status
The Red LED labeled “STATUS” is provided to indicate system faults.
Steady ON: Control OK
Steady OFF: No power
Rapid flash: False flame or internal control fault
One flash: Limit switch is open
Two flashes: Pressure switch is open
Three flashes: Pressure switch is stuck closed
Four flashes: Lockout due to failed ignition
Five flashes: L1 neutral reversed or L1 voltage
not present on L1
Flame Status
A Yellow LED labeled “Flame” is provided to indicate flame status. When
flame is sensed, the flame LED is lit. If flame sense is weak, yellow LED
will flash.
Control Module Status Indicator - M1S* Series
The indicator light on the oil primary control provides lockout, recycle,
and cad cell indications as follows:
1. Flashing 1/2 second on, 1/2 second off - system is locked out or
in restricted mode.
2. Flashing 2 seconds on, 2 seconds off - control is in recycle mode.
3. Indicator light is on - cad cell is sensing flame.
4. Indicator light is off - cad cell is not sensing flame.
c. Check the flue for any blockages or loose
connections.
d. Check the combustion air passages for block-
age.
High Gas Bills
a. Be sure the proper orifices are being used.
b. Be sure the return air system is clear and free
of blockage.
c. Be sure the furnace filter is clean.
d. Be sure the home is insulated, that windows
and doors fit tightly, and that there are no
leaks in the heating duct system.
e. Check the room thermostat to be sure the
setting is not higher than necessary. Low
Control Module Status Indicator - M1B
a. One flash-the control is in lock-out because the inducer centrifu
gal switch is or was stuck closed.
b. Two flashes-the control is in lockout because the signal was not
received by the control that the inducer centrifugal switch had
closed within the time.
c. Three flashes-the control is in lockout because a failed ignition
attempt, a gas valve error, or a false flame sensed during the warm
up period. If false flame has been sensed, the control will return to
normal operation, and repeat ignition sequence when the false flame
is not present.
d. Four flashes-the control is in lockout due to a failure within the control
board.