Carrier /50HC 04-28, Controls, Start-Up, Operation And Troubleshooting, Page: 55 / 144

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Fig. 17 — IGC Service Analysis Logic
1 FLASH - INDOOR FAN DELAY
MODIFIED (HEATING)
2 FLASHES - OPENING OF LIMIT
SWITCH
3 FLASHES - FLAME SENSOR
INDICATES FLAME WITH
CLOSED GAS VALVE
4 FLASHES - LIMIT SWITCH
CYCLED 4 TIMES ON SINGLE
CALL FOR HEAT
5 FLASHES - IGNITION LOCKOUT
(No ignition within 15 minutes)
6 FLASHES - INDUCED DRAFT
MOTOR FAULT
(No signal from the Hall Effect
Sensor or 60 seconds)
7 FLASHES - OPENING OF
ROLLOUT SWITCH
8 FLASHES - HARDWARE OR
SOFTWARE FAULT
9 FLASHES - SOFTWARE
LOCKOUT
FLASHING LED is
ON
CALL FOR
24 VOLTS
BETWEEN
F1 AND C
YES
No
DEFECTIVE
IGC BOARD
1. BLOWN 5 AMP FUSE
2. DEFECTIVE 24V TRANS.
3. BROKEN WIRE
4. NO POWER TO UNIT
HEATING
‘W1’ FROM BASE CONTROL BOARD ENERGIZES ‘W’
ON IGC - 1 MINUTE LOCK-ON
COMBUSTION RELAY ON IGC IN ENERGIZED
COMBUSTION RELAY ENERGIZES INDUCED DRAFT MOTOR (IDM) THROUGH
TERMINAL ′CM′ ON IGC
IF IDM IS TURNING AT CORRECT SPEED (AT LEAST 2400 RPM), HALL
EFFECT SENSOR SENDS CORRECT SIGNAL TO TERMINAL ‘J1’ ON IGC
IF LIMIT SWITCH AND ROLLOUT
SWITCH ARE CLOSED, IGC SAFETY
LOGIC WILL INITIATE IGNITION
SEQUENCE
IGC HIGH VOLTAGE
TRANSFORMER CREATES A
10,000 VOLT SPARK FOR 5
SECONDS
IGC SAFETY LOGIC OPENS GAS
VALVE FOR 5 SECONDS
DOES IGC DETECT
.2 MICROAMPS FOR 2
SECONDS
No
Yes
AFTER 45 SECONDS (OR LESS IF THE TIMING
HAS BEEN REDUCED DUE TO LIMIT SWITCH
TRIPS) IGC WILL ENERGIZE BLOWER RELAY
DID LIMIT
SWITCH OPEN BEFORE THE 45
SECONDS (OR THE MODIFIED
TIME) HAS TIMED OUT?
Yes
No
No
IGC SAFETY LOGIC WILL SHUT
OFF GAS VALVE AND SPARK
20 SECOND PURGE OF HEAT
EXCHANGER
IS THIS THE
33RD RETRY? (OR 15
MINUTES)
Yes
IGNITION LOCKOUT
(5 FLASHES OF LED)
SUBTRACT 5 SECONDS (OR
ANOTHER 5 SECONDS) FROM
INDOOR FAN ON TIME DELAY
NORMAL HEATING OPERATION
HEATING DEMAND SATISFIED
45 SECOND BLOWER SHUTOFF DELAY
(DELAY EXTENDED BY 5 SECONDS FOR EACH LIMIT SWITCH TRIP
MAXIMUM DELAY: 3 MINUTES)
IDM STOPS, SAFETY LOGIC SHUTS OFF GAS VALVE
LEGEND
IDM – Induced-Draft Motor
IGC – Integrated Gas Unit Controller
NOTE: Thermostat Fan Switch in the
“AUTO” position.
OFF