Carrier 50PG20-28 Controls, Start-Up, Operation, Service And Troubleshooting Instructions page 62

Table 48 -- IGC Board LED Alarm Codes
LED FLASH DESCRIPTION ACTION TAKEN BY RESET METHOD PROBABLE CAUSE
CODE CONTROL
On Normal Operation -- -- --
Off Hardware Faiture No gas heating -- Loss of power to the IGC Check 5 amp fuse on IGC,
)ower to unit, 24V circuit breaker, transformer, and wir-
ing to the IGC.
1 Flash Indoor Fan On/Off Delay 5 seconds subtracted from On Power reset High temperature limit switch opens during heat
Modified delay, exchanger warm-up period before fan-on deIay expires
5 seconds added to Off delay High temperature limit switch opens within
(3 min max) 10 minutes of heat call (W) Off
See Limit Switch Fautt
2 Flashes Limit Switch Fault Gas vaIve and igniter Off Limit switch closed, or heat High temperature limit switch is open Check the opera-
Indoor fan and inducer On call (W) Off 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 The IGC sensed a flame when the gas vaIve should be
Power reset for LED reset closed. Check wiring, flame sensor, and gas valve oper-
ation
4 Flashes Four Consecutive Limit Switch No gas heating Heat caII (W) Off 4 consecutive limit switch faults within a single call for
Fault Power reset for LED reset heat. See Limit Switch Fault.
5 Flashes Ignition Fault No gas heating Heat caII (W) Off Unit unsuccessfully attempted ignition for 15 minutes.
Power reset for LED reset 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 Inducer sense normal, or Inducer sense On when heat call Off, or inducer sense
If heat on: gas valve Off and heat call (W) Off Off when heat call On. Check wiring, voltage, and oper-
inducer On. ation of IGC motor Check speed sensor wiring to IGC
7 Flashes Rotlout Switch Lockout Gas valve and igniter Off Power reset Rollout switch has opened Check gas valve operation.
Indoor fan and inducer On Check induced-draft blower wheel is properly secured to
motor shaft.
8 Flashes Internal Controt Lockout No gas heating Power reset. IGC has sensed internal hardware or software error If
fault is not cteared by resetting 24 v power, replace the
IGC.
9 Flashes Temporary Software Lockout No gas heating 1 hour auto reset, or power Electrical interference is disrupting the IGC
reset, software
LEGEND
IGC -- Integrated Gas Unit Control
LED -- Light-Emitting Diode
NOTES:
1 There is a 3-second pause between alarm code displays
2 If more than one alarm code exists, atl applicable alarm codes wiIt be dis-
played in numerical sequence.
3 Alarm codes on the IGC witl be lost if power to the unit is interrupted.
Table 49 -- Electric Heat Service Analysis
PROBLEM CAUSE REMEDY
Heat Will Not Turn On. Active alarm. Check active alarms using ComfortLink
TM
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 Check using ComfortLink Scrolling Marquee
changeover time
Thermostat or occupancy schedule setpoint not calling for Check using ComfortLink Scrolling Marquee
heating.
Heat forced off in Service Test mode.
No 24 vac at heater contactor
Check using ComfortLink Scrolling Marquee. Turn Service Test
mode off.
Check transformer and circuit breaker.
Check auto-reset timit switches on heater
Check manual-reset timit switch (LS) on heater.
Check minimum airflow Check limit switch when it is coot,
replace if open
Replace air filters
Atlow time for W2 to energize.
Open temperature timit switch on heater.
Inadequate Heating. Dirty air fitters.
Thermostat or occupancy schedule setpoint only calling
forWl.
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 vottage 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 schedute setpoint stilt calling for Check using ComfortLink Scrolling Marquee
heating.
Heat forced on in Service Test mode. Check using ComfortLink Scrolling Marquee. Turn Service Test
mode off.
Heater contactor faiIed. Power off unit Check contactor and reptace if closed
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