What does Heil code 3 Flash mean?
Heil furnace code 3 Flash means the low-pressure switch was open when the control expected it to be closed on the supported control family. Confirm the model number and diagnostic chart inside the furnace door before replacing parts.
What causes Heil code 3 Flash?
- A blocked intake or exhaust vent
- A restricted condensate drain or pressure hose
- A weak inducer motor or pressure switch
Can I troubleshoot Heil code 3 Flash?
- With the furnace off, check outdoor intake and exhaust openings for snow, ice, leaves, or nests.
- Replace a visibly dirty air filter, restore power once, and note whether the code returns.
How much does Heil code 3 Flash cost to fix?
A pressure switch replacement typically costs between $175 and $900 nationally.
When should I call a technician?
Call a technician if the vent is clear and the pressure-switch code returns; combustion-air testing requires instruments.
Symptoms this code causes
Sources and model scope
Fault codes vary by model and control board. Confirm the diagnostic chart inside your furnace panel or the official manual before acting.
Scope used here: ICP control boards covered by document 44001202103 and using its 2–10 flash table.
- International Comfort Products: Furnace Control Board Diagnostic Codes
44001202103 · ICP furnace control boards covered by document 44001202103; confirm the control-board label and door chart.
Compiled by Warmlo Editorial · Reviewed August 2026
This is general information, not professional advice. Gas, electrical, and combustion repairs can be dangerous — when in doubt, call a licensed technician.