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Table 18 – IGC Board LED Alarm Codes
LED
FLASH
CODE
DESCRIPTION
ACTION TAKEN BY
CONTROL
RESET METHOD PROBABLE CAUSE
On Normal Operation
— — —
Off Hardware Failure No gas heating.
—
Loss of power to the IGC. Check 5 amp fuse on IGC,
power to unit, 24V circuit breaker, transformer, and
wiring to the IGC.
1Flash Indoor Fan On/Off Delay
Modified
5 seconds subtracted from
On delay.
5 seconds added to Off
delay (3 min max).
Power reset. High temperature limit switch opens during heat
exchanger warm-up period before fan-on delay
expires.
High temperature limit switch opens with in
10 minutes of heat call (W) Off.
See Limit Switch Fault.
2Flashes Limit Switch Fault Gas valve an d igniter Off.
Indoor fan and inducer On.
Limit switch closed, or
heat call (W) Off.
High temperature limit switch is open. Check the
operation of the indoor (evaporator) fan motor.
Ensure that the supply-air temperature rise is within
the range on the unit nameplate. Check wiring and
limit switch operation.
3Flashes Flam e Sense Fault Indoor fan and inducer On. Flame sense normal.
Power reset for LED
reset.
TheIGCsensedaflamewhenthegasvalveshould
be closed. Check wiring, flame sensor, and gas valve
operation.
4Flashes Four Consecutive Limit
Switch Fault
No gas heating. Heat call (W) Off.
Power reset for LED
reset.
4 consecutive limit switch faults within a single call for
heat. See Limit Switch Fault.
5Flashes Ignition Fault No gas heating. Heat call (W) Off.
Power reset for LED
reset.
Unit unsuc c essfully attempted ignitio n for 15 minutes .
Check igniter and flame sensor electrode spacing, gap s,
etc. Check flame sens e and igniter wiring . Check g as
valve oper ation and gas supp ly.
6Flashes Induced Draft Motor
Fault
If heat off: no gas heating.
If h eat on: gas valve Off
and inducer On.
Inducer sense normal, or
heat call (W) Off.
Inducer sense On when heat call Off, or inducer
sense Off when heat call On. Check wiring, voltage,
and operation of IGC motor. Check speed sensor
wiring to IGC.
7Flashes Rollout Switch Lockout Gas valve and igniter Off.
Indoor fan and inducer On.
Power reset. Rollout switch has opened. Check gas valve
operation. Check induced-draft blower wheel is
properly secured to motor shaft.
8Flashes Internal Control Lockout No gas heating. Power reset. IGC has sensed internal hardware or software error. If
fault is not cleared by resetting 24 v power, replace
the IGC.
9Flashes Temporary Software
Lockout
No gas heating. 1 hour a uto reset, or
power reset.
Electrical interference is disrupting the IGC software.
LEGEND
IGC --- Integrated Gas Unit Control
LED --- L i g h t --- E m i t t i n g D i o d e
NOTES:
1. T h er e is a 3---second pause between alarm code displays.
2. If more than one alarm code exists, al l applicable alarm codes will be
displayed in numerical sequence.
3. Alarm codes on the IGC will be lost if power to the unit is interrupted.
Table 19 – Electric Heat Service Analysis
PROBLEM CAUSE REMEDY
Heat Will Not Turn On.
Active alarm. Check active alarms using SystemVu™ Display.
Unit is NOT configured for heat. Check heating configurations using the SystemVu Display
No power to unit. Check power supply, fuses, wiring, and circuit breakers.
Unit is in minimum heat off-time, or minimum cool-heat
changeover time.
Check using SystemVu Display .
Thermostat or occupancy schedule setpoint not
calling for heating.
Check using SystemVu Display .
Heat forced off in Service Test mode. Check using SystemVu Display. T urn Service Test mode off.
No 24 VAC a t heater contactor.
Check transformer and circuit breaker.
Check auto-reset limit switches on heater.
Check manual-reset limit switch (LS) on indoor fan housing.
Open temperature limit switch on heater . Check minimum airflow . Check limit switch when it is cool,
replace if open.
Inadequate Heating.
Dirty air filters. Replace air filters.
Thermostat or occupancy schedule setpoint only
calling for W1.
Allow time for W2 to energize or adjust setpoints.
Heat un dersized for load. Decrease load or increase size of heater .
Restricted airflow Remove restriction. Check SAT compared to the SAT
heating limits.
Too much outdoor air. Check economizer position and configuration. Adjust
minimum position.
Limit switch cycles heaters. Check rotation of blower and minimum airflow.
Bad heater elements. Power off unit and remove high voltage wires. Check
resistan ce of element, replace if open.
Heat Will Not Turn Off.
Unit is in minimum heat on-time. Check using SystemVu Display.
Thermostat or occupancy schedule setpoint still
calling for heating.
Check using SystemVu Display .
Heat forced on in Service Test mode. Check using SystemVu Display. Turn Service Test mode off.
Heater contactor failed. P ower off unit. Check contactor and replace if closed.
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