Carrier 48FC Series Controls, Start-Up, Operation And Troubleshooting page 40

LED
FLASH DESCRIPTION
CODE
On Normal Operation
Off Hardware Failure
1 Flash Indoor Fan On/Off Delay
Modified
2 Flashes Limit Switch Fault
3 Flashes Flame Sense Fault
4 Flashes Four Consecutive Limit
Switch Fault
5 Flashes Ignition Fault
6 Flashes Induced Draft Motor
Fault
7 Flashes Rollout Switch Lockout
8 Flashes Internal Control Lockout
9 Flashes Temporary Software
Lockout
LEGEND
IGC --- Integrated Gas Unit Control
LED --- Light---Emitting Diode
PROBLEM
Heat Will Not Turn On.
Inadequate Heating.
Heat Will Not Turn Off.
Table 18 – IGC Board LED Alarm Codes
ACTION TAKEN BY
CONTROL
—
No gas heating.
5 seconds subtracted from
On delay.
5 seconds added to Off
delay (3 min max).
Gas valve and igniter Off.
Indoor fan and inducer On.
Indoor fan and inducer On.
No gas heating.
No gas heating.
If heat off: no gas heating.
If heat on: gas valve Off
and inducer On.
Gas valve and igniter Off.
Indoor fan and inducer On.
No gas heating.
No gas heating.
Table 19 – Electric Heat Service Analysis
CAUSE
Active alarm.
Unit is NOT configured for heat.
No power to unit.
Unit is in minimum heat off-time, or minimum cool-heat
changeover time.
Thermostat or occupancy schedule setpoint not
calling for heating.
Heat forced off in Service Test mode.
No 24 VAC at heater contactor.
Open temperature limit switch on heater.
Dirty air filters.
Thermostat or occupancy schedule setpoint only
calling for W1.
Heat undersized for load.
Restricted airflow
Too much outdoor air.
Limit switch cycles heaters.
Bad heater elements.
Unit is in minimum heat on-time.
Thermostat or occupancy schedule setpoint still
calling for heating.
Heat forced on in Service Test mode.
Heater contactor failed.
RESET METHOD
—
Loss of power to the IGC. Check 5 amp fuse on IGC,
—
power to unit, 24V circuit breaker, transformer, and
wiring to the IGC.
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.
Limit switch closed, or High temperature limit switch is open. Check the
heat call (W) Off. 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.
Flame sense normal. The IGC sensed a flame when the gas valve should
Power reset for LED be closed. Check wiring, flame sensor, and gas valve
reset. operation.
Heat call (W) Off. 4 consecutive limit switch faults within a single call for
Power reset for LED heat. See Limit Switch Fault.
reset.
Heat call (W) Off. Unit unsuccessfully attempted ignition for 15 minutes.
Power reset for LED Check igniter and flame sensor electrode spacing, gaps,
reset. etc. Check flame sense and igniter wiring. Check gas
valve operation and gas supply.
Inducer sense normal, or Inducer sense On when heat call Off, or inducer
heat call (W) Off. sense Off when heat call On. Check wiring, voltage,
and operation of IGC motor. Check speed sensor
wiring to IGC.
Power reset. Rollout switch has opened. Check gas valve
operation. Check induced-draft blower wheel is
properly secured to motor shaft.
Power reset. IGC has sensed internal hardware or software error. If
fault is not cleared by resetting 24 v power, replace
the IGC.
1 hour auto reset, or Electrical interference is disrupting the IGC software.
power reset.
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
displayed in numerical sequence.
3. Alarm codes on the IGC will be lost if power to the unit is interrupted.
Check active alarms using SystemVu™ Display.
Check heating configurations using the SystemVu Display
Check power supply, fuses, wiring, and circuit breakers.
Check using SystemVu Display.
Check using SystemVu Display.
Check using SystemVu Display. Turn Service Test mode off.
Check transformer and circuit breaker.
Check auto-reset limit switches on heater.
Check manual-reset limit switch (LS) on indoor fan housing.
Check minimum airflow. Check limit switch when it is cool,
replace if open.
Replace air filters.
Allow time for W2 to energize or adjust setpoints.
Decrease load or increase size of heater.
Remove restriction. Check SAT compared to the SAT
heating limits.
Check economizer position and configuration. Adjust
minimum position.
Check rotation of blower and minimum airflow.
Power off unit and remove high voltage wires. Check
resistance of element, replace if open.
Check using SystemVu Display.
Check using SystemVu Display.
Check using SystemVu Display. Turn Service Test mode off.
Power off unit. Check contactor and replace if closed.
40
PROBABLE CAUSE
—
REMEDY