International comfort products N9MP1 Service Manual page 27

Single Stage Multi Position Furnace
Heating Request with Gas Shut Off:
24 VAC signal applied to W terminal of FCB.
The FCB will attempt 4 cycles for ignition then go to soft lockout for 3 hours then try for ignition again as long as the heat
call remains. Power reset will clear lockout.
•
Inducer motor turns on
•
Following a 15 second prepurge delay, the igniter begins warm up.
•
The igniter glows red−hot for 22 seconds, then turns off. The FCB flashes error code 6.
•
The igniter stays off for 17 seconds, then begins to warm up again.
•
The igniter glows red hot for 22 seconds then turns off. The FCB continues flashing error code 6.
•
The igniter stays off for 17 seconds, then begins to warm up again.
•
The igniter glows red hot for 22 seconds then turns off. The FCB continues flashing error code 6.
•
The igniter stays off for 17 seconds, then begins to warm up again.
•
The igniter glows red hot for 22 seconds then turns off. The FCB proceeds to soft lockout and stops flashing error code
6 and begins flashing error code 6 + 1.
•
The inducer motor de−energizes after a 15 second post purge.
Control Board Diagnostic Codes (See Figure 30)
OFF = 24VAC or 115VAC is off, fuse is open
Heartbeat = Normal operation or no previous Diagnostic Code
ON SOLID = Soft Lockout − Furnace Control Error (1 hr delay)
If code repeats immediately following power reset then replace control
1 Flash = Not used
2 Flashes = Pressure switch(es) closed when should be open
3 Flashes = Pressure switch open when should be closed
4 Flashes = Limit or roll−out switch open (less than 2 minutes)
5 Flashes = Flame sensed out of sequence
6 Flashes = Failure to ignite or flame sense lost while running
6 + 1 Flashes = Soft Lockout − Max trials for ignition reached (3hr delay)
7 Flashes = Soft Lockout − Limit or roll−out switch open longer than 2 minutes (1 hr delay)
(roll−out switch requires manual reset)
8 Flashes = Permanent Lockout − Gas valve relay contact stuck closed or miswired gas valve (power reset only)
10 Flashes = Line voltage (115VAC) polarity reversed. If twinned, refer to twinning kit instructions
* If status code recall is needed, briefly (2−3 seconds) remove then reconnect one limit switch wire (main or rollout) to display
last stored status code. Do not remove power or blower door before initiating status code recall or code will be lost. Code is
automatically cleared after 72 hours or upon power reset.
* Proper flame sense microamps: 0.7 microamps D.C. minimum, 2.0 − 4.0 microamps nominal
Figure 30 Furnace Control Board
24 VAC
HUM
Diagnostic Light
FUSE
440 08 2011 00
115 VAC
HUM
Service Manual
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