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Table 95 — Gas Heating Service Analysis
Table 96 — Electric Heat Service Analysis
PROBLEM CAUSE REMEDY
Burners Will Not Ignite. Active alarm. Check active alarms using ComfortLink™ scrolling
marquee.
No power to unit. Check power supply, fuses, wiring, and circuit breakers.
No power to IGC (Integrated Gas Control). Check fuses and plugs.
Heaters off due to time guard to prevent short
cycling.
Check using ComfortLink scrolling marquee.
Control calling for Cooling. Check using ComfortLink scrolling marquee.
No gas at main burners. Check gas line for air and purge as necessary. After purg-
ing gas line of air, allow gas to dissipate for at least 5 min-
utes before attempting to re-light unit.
Water in gas line. Drain water and install drip.
Inadequate Heating. Dirty air filters. Replace air filters.
Gas input too low. Check gas pressure at manifold. Refer to gas valve adjust-
ment in Installation, Start-up, and Service Manual.
Control calling for W1only (low heat). Allow time for W2 to energize.
Unit undersized for load. Decrease load.
Restricted airflow. Remove restriction.
Too much outdoor air. Check economizer position and configuration. Adjust mini-
mum position using ComfortLink scrolling marquee.
Limit switch cycles main burners. Check rotation of blower, thermostat heat anticipator set-
tings, and temperature rise of unit. Adjust as needed.
Poor Flame Characteristics. Incomplete combustion (lack of combustion air)
results in: Aldehyde odors, CO, sooting flame, or
floating flame.
Check all screws around flue outlets and burner compart-
ment. Tighten as necessary.
Cracked heat exchanger, replace.
Unit is over-fired, reduce input. Adjust gas line or manifold
pressure.
Check vent for restriction. Clean as necessary.
Check orifice to burner alignment.
Burners Will Not Turn Off. Unit is in minimum on-time. Check using ComfortLink scrolling marquee.
Unit running in Service Test mode. Check using ComfortLink scrolling marquee.
PROBLEM CAUSE REMEDY
No Heat. Power failure. Call power company.
Fuse blown or circuit breaker tripped. Replace fuse or reset circuit breaker.
Thermostat occupancy schedule set point not call-
ing for Heating.
Check using ComfortLink scrolling marquee.
No 24 vac at primary contactor. Check transformer and circuit breaker.
No power (high voltage) to L2 of primary contactor. Check safety switches “one-shot” backup and auto limit.
Bad electrical elements. Power off unit and remove high voltage wires. Check resis-
tance of heater, replace if open.