27
Call for heat,
t-stat closes R-W
Check for red light
on circuit board
24 Volt, C to W
on circuit board
Polarity
is reversed
Switch L1 & L2
Inducer starts
Check fuse on
circuit board,
replace if no
continuity
Check for voltage
at inducer molex plug
Pressure switch
stuck closed
Replace
Board
Replace
pressure switch
Circuit board 3 blinks
Check for voltage
at molex plug
Replace Inducer
Blower
Pressure switch
closes within
10 seconds
Circuit board
blinks 2 times
Is there >8mA on W terminal
of circuit board? Replace t-stat or
add isolation relay.
Pressure switch
open
Inducer pre-purges
for 45 seconds
Greater than
-.30" W.C.
differential at pressure switch
Replace pressure switch
Check venting
Ignitor heats up
and glows for
30 seconds
Gas valve open
Do Burners Light
Ignitor turns off 7 seconds
after gas valve opens
Main blower starts after
delay time (30 seconds)
Flame, inducer, main blower
stay on until call for heat ends
Replace ignitor
Replace circuit board
24 volts at gas valve.
Insure lever is in
ON position. Insure gas inlet
pressure is below 14" W.C.
Replace gas valve
Manifold Gas
Pressure Available
Burners stay on
longer than 6 seconds
Check and adjust ignitor
gap to 5/16"
Will retry 4 more times.
Soft lock out blinks 4 times
on status light.
Power down and
back up to reset.
Replace board
Flame light on
Replace circuit board
Check for voltage at
com and heat terminals
Replace circuit board
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Check motor
and capacitor
Yes
No
No
No
No
No
No
No
No
No
No
No
No
No
No
Flashing
OFF
No
No
No
No
No
Is light blinking
5 times?
Adjust ignitor gap to 5/16"
Check ground circuit to
Furnace.
Flame light blinks at
1 uA(weak signal)
Note:
Retry
Every
Hour
Inducer post-purges
for 30 seconds
Main Blower Fan Off Timing
Troubleshooting Sequence – M1M
