MEDIUM URGENCY

Heil 4 Flashes - Limit Circuit Open

4 flashes

Limit circuit open - overheating. Usually restricted airflow.

Brand: Heil (Also covers Tempstar, Comfortmaker, Keeprite, ICP, Day & Night, Arcoaire) | Equipment: Gas Furnace

What This Code Means

4 LED flashes on Heil/Tempstar/Comfortmaker furnaces means the limit circuit is open. The high temperature switch tripped due to overheating in the heat exchanger.

Likely Causes (Ranked)

Most common (~70%)

Dirty air filter

What: Restricted airflow.

How to check: Inspect filter.

Fix: Replace filter.

Shop parts

Common

Closed registers

What: Static pressure spike.

How to check: Open all vents.

Fix: Clear vents.

Common

Failed blower

What: Weak airflow.

How to check: Feel airflow at register.

Fix: Replace motor.

Shop parts

Diagnostic Steps

Cut power 30s
Replace filter
Open all vents
Watch for code return
Check blower if persists

Frequently Asked Questions

Why does Heil 4 flashes keep coming?

Furnace overheating. Filter resolves 70% of cases.

Same on Tempstar/Comfortmaker?

Yes - all ICP family use these codes.

DIY?

Filter and vents yes.

Related Heil Codes

Related Symptoms

Need More Help?

Try our interactive symptom diagnostic tool or browse Heil parts.

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