What does Coleman code 3 Blinks mean?
Coleman furnace code 3 Blinks means the pressure switch failed to close after the inducer started on the supported control family. Confirm the model number and diagnostic chart inside the furnace door before replacing parts.
What causes Coleman code 3 Blinks?
- A blocked intake or exhaust vent
- A restricted condensate drain or pressure hose
- A weak inducer motor or pressure switch
Can I troubleshoot Coleman code 3 Blinks?
- 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 Coleman code 3 Blinks 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.
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: Johnson Controls integrated furnace controls using the documented 1–12 red-flash table.
- Johnson Controls Unitary Products: Gas Furnace Installation Manual
272441-UIM-E-0513 · Johnson Controls integrated furnace controls with the 1–12 red-flash table in this manual; other model families may differ.
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.