62
Table 48 — IGC Board LED Alarm Codes
LEGEND
NOTES:
1. There is a 3-second pause between alarm code displays.
2. If more than one alarm code exists, all applicable alarm codes will be dis-
played in numerical sequence.
3. Alarm codes on the IGC will be lost if power to the unit is interrupted.
Table 49 — Electric Heat Service Analysis
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 wir-
ing to the IGC.
1 Flash
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 within
10 minutes of heat call (W) Off.
See Limit Switch Fault.
2 Flashes
Limit Switch Fault
Gas valve and igniter Off.
Indoor fan and inducer On.
Limit switch closed, or heat
call (W) Off.
High temperature limit switch is open. Check the opera-
tion 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.
3 Flashes
Flame Sense Fault
Indoor fan and inducer On.
Flame sense normal.
Power reset for LED reset.
The IGC sensed a flame when the gas valve should be
closed. Check wiring, flame sensor, and gas valve oper-
ation.
4 Flashes
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.
5 Flashes
Ignition Fault
No gas heating.
Heat call (W) Off.
Power reset for LED reset.
Unit unsuccessfully attempted ignition for 15 minutes.
Check igniter and flame sensor electrode spacing, gaps,
etc. Check flame sense and igniter wiring. Check gas
valve operation and gas supply.
6 Flashes
Induced Draft Motor Fault
If heat off: no gas heating.
If heat 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 oper-
ation of IGC motor. Check speed sensor wiring to IGC.
7 Flashes
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.
8 Flashes
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.
9 Flashes
Temporary Software Lockout
No gas heating.
1 hour auto reset, or power
reset.
Electrical interference is disrupting the IGC
software.
IGC
— Integrated Gas Unit Control
LED
— Light-Emitting Diode
PROBLEM
CAUSE
REMEDY
Heat Will Not Turn On.
Active alarm.
Check active alarms using ComfortLink™ Scrolling Marquee.
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 ComfortLink Scrolling Marquee.
Thermostat or occupancy schedule setpoint not calling for
heating.
Check using ComfortLink Scrolling Marquee.
Heat forced off in Service Test mode.
Check using ComfortLink Scrolling Marquee. Turn Service Test
mode off.
No 24 vac at heater contactor.
Check transformer and circuit breaker.
Check auto-reset limit switches on heater.
Check manual-reset limit switch (LS) on heater.
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.
Heat undersized for load.
Decrease load or increase size of heater.
Restricted airflow
Remove restriction.
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 resistance
of element, replace if open.
Heat Will Not Turn Off.
Unit is in minimum heat on-time.
Check using ComfortLink Scrolling Marquee.
Thermostat or occupancy schedule setpoint still calling for
heating.
Check using ComfortLink Scrolling Marquee.
Heat forced on in Service Test mode.
Check using ComfortLink Scrolling Marquee. Turn Service Test
mode off.
Heater contactor failed.
Power off unit. Check contactor and replace if closed.
Summary of Contents for 48PG24
Page 68: ...68 Fig 14 Low Voltage Control Schematic 48PG20 28 Units without Humidi MiZer System a48 7627...
Page 69: ...69 Fig 15 Low Voltage Control Schematic 48PG20 28 Units with Humidi MiZer System a48 8227...
Page 70: ...70 Fig 16 Low Voltage Control Schematic 50PG20 28 Units without Humidi MiZer System a48 7778...
Page 71: ...71 Fig 17 Low Voltage Control Schematic 50PG20 28 Units with Humidi MiZer System a50 8101...
Page 72: ...72 Fig 18 Power Schematic Units without Humidi MiZer System a48 7628...
Page 73: ...73 Fig 19 Power Schematic Units with Humidi MiZer System a48 8228...
Page 74: ...74 Fig 20 Component Arrangement Units without Humidi MiZer System a48 8229...
Page 75: ...75 Fig 21 Component Arrangement Units with Humidi MiZer System a48 8230...
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