What does Coleman code 4 Blinks mean?
Coleman furnace code 4 Blinks means the primary or auxiliary limit circuit is open on the supported control family. Confirm the model number and diagnostic chart inside the furnace door before replacing parts.
What causes Coleman code 4 Blinks?
- A dirty or overly restrictive air filter
- Closed or blocked supply and return vents
- A blower, limit switch, or airflow problem
Can I troubleshoot Coleman code 4 Blinks?
- Turn the furnace off and replace a dirty filter with the size and type specified for the system.
- Open all supply registers and make sure return grilles are not blocked before trying one reset.
How much does Coleman code 4 Blinks cost to fix?
A limit switch replacement typically costs between $150 and $750 nationally.
When should I call a technician?
Call a technician if the limit code returns; repeated overheating can damage the furnace.
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.