PGD4, PGS4, Series G, H WPG4 Series D, H Ultra Low NOx: Installation Instructions
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
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*WARNING : If the IGC must be replaced, be sure to ground yourself to dissipate any electrical charge that my be present before handling new control board. The IGC is sensitive to static
electricity and my be damaged if the necessary precautions are not taken.
IMPORTANT: Refer to Table 15-Troubleshooting Guide-Heating for additional troubleshooting analysis.
LEGEND
IGC—Integrated Gas Unit Controller
LED—Light-Emitting Diode
Table 14 – Troubleshooting Guide–Heating
SYMPTOM CAUSE REMEDY
Burners will not ignite
Water in gas line Drain. Install drip leg.
No power to furnace Check power supply fuses, wiring or circuit breaker.
No 24-v power supply to control circuit
Check transformer.
NOTE: Some transformers have internal over-current protection
that requires a cool-down period to reset.
Mis-wired or loose connections Check all wiring and wire nut connections
Misaligned spark electrodes
Check flame ignition and sense electrode positioning.
Adjust as necessary.
No gas at main burners
1. Check gas line for air. Purge as necessary. NOTE: After
purging gas line of air, wait at least 5 minutes for any gas to
dissipate before attempting to light unit.
2. Check gas valve.
Inadequate heating
Dirty air filter Clean or replace filter as necessary
Gas input to furnace too low
Check gas pressure at manifold match with that on unit
nameplate
Unit undersized for application Replace with proper unit or add additional unit
Restricted airflow Clean or replace filter. Remove any restriction.
Limit switch cycles main burners
Check rotation of blower, temperature rise of unit. Adjust as
necessary.
Table 15 – Troubleshooting Guide–LED Status Codes
SYMPTOM CAUSE REMEDY
No Power or Hardware failure
(LED OFF)
Loss of power to control module (IGC)*.
Check 5-amp fuse son IGC*, power to unit, 24-v circuit
breaker, and transformer. Units without a 24-v circuit breaker
have an internal overload in the 24-v transformer. If the
overload trips, allow 10 minutes for automatic reset.
Check fuse, low voltage circuit
(LED 1 flash)
Fuse is blown or missing or short circuit in
secondary (24VAC) wiring.
Replace fuse if needed. Verify no short circuit in low voltage
(24 VAC wiring).
Limit switch faults
(LED 2 flashes)
High temperature limit switch is open.
Check the operation of the indoor (evaporator) fan motor.
Ensure that the supply-air temperature rise is in accordance
with the range on the unit nameplate. Clean or replace filters.
Flame sense fault
(LED 3 flashes)
The IGC* sensed flame that should not be
present.
Reset unit. If problem persists, replace control board.
4 consecutive limit switch faults
(LED 4 flashes)
Inadequate airflow to unit.
Check the operation of the indoor (evaporator) fan motor and
that supply-air temperature rise agrees with range on unit
nameplate information.
Ignition lockout fault
(LED 5 flashes)
Unit unsuccessfully attempted ignition for 15
minutes.
Check ignitor and flame sensor electrode spacing, gaps, etc.
Ensure that fame sense and ignition wires are properly
terminated. Verify that unit is obtaining proper amount of gas.
Verify that the intake tube, perforated holes on the burner
box top, and the burner box baffle are aligned.
Pressure Switch fault
(LED 6 flashes)
Open pressure switch.
Verify wiring connections to pressure switch and inducer
motor. Verify pressure switch hose is tightly connected to
both inducer housing and pressure switch. Verify inducer
wheel is properly attached to inducer motor shaft. Verify
inducer motor shaft is turning.
Rollout Switch fault (Standard and Low
NOx models)
Burner Thermal Switch fault (Ultra Low
NOx)
(LED 7 flashes)
Rollout switch has opened.
Rollout switch will automatically reset, but IGC* will continue
to lockout unit. Check gas valve operation. Ensure that
induced-draft blower wheel is properly secured to motor
shaft. Verify that the intake tube, perforated holes on the
burner box top, and the burner box baffle are aligned. Reset
unit at unit disconnect.
Internal control fault
(LED 8 flashes)
Microprocessor has sensed an error in the
software or hardware.
If error code is not cleared by resetting unit power, replace
the IGC*.
Temporary 1 hr auto reset
1
(LED 9 flashes)
Electrical interference impeding IGC software
Reset 24-v. to control board or turn thermostat off, then on
again. Fault will automatically reset itself in one (1) hour.
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