What does Tempstar 1 Flash mean?

On a Tempstar packaged gas/electric unit, the integrated gas unit controller (IGC) LED flashing once signals a limit switch fault.

What does Tempstar 2 Flashes mean?

On a Tempstar packaged gas/electric unit, the integrated gas unit controller (IGC) LED flashing twice indicates a flame sense fault.

What does Tempstar 3 Flashes mean?

On a Tempstar packaged gas/electric unit, the integrated gas unit controller (IGC) LED flashing three times indicates four consecutive limit switch faults.

What do Tempstar furnace LED flash codes mean?

Tempstar 80%/90%+ gas furnaces blink an amber Status LED on the SmartLight integrated furnace control (IFC), visible through a viewport on the lower blower-door panel. Count the flashes between long pauses: 1 flash = blower door switch open, 2 flashes = external lockout (failed ignition retries), 3 flashes = pressure switch stuck open or closed wrongly, 4 flashes = primary or auxiliary limit switch open, 5 flashes = flame sensed without a call for heat, 6 flashes = ignition proven then lost, 7 flashes = gas valve circuit fault, 8 flashes = low flame-sense current, 9 flashes = line-voltage polarity reversed or low secondary voltage. Multi-digit codes (11, 12, 13) indicate inducer, blower amp, or limit-lockout faults on newer two-stage and modulating boards. Open the blower door label or the IOM for the exact chart — wording varies slightly by model year and series.

What does 4 flashes mean on a Tempstar furnace?

Four flashes on the SmartLight IFC means the primary or auxiliary high-limit switch opened — the heat exchanger or supply plenum exceeded the safety setpoint, or a flame-rollout switch tripped at the burner box. Most common causes are restricted airflow (dirty filter, blocked return, closed registers, undersized return duct), a slipping or failed blower motor or capacitor, an undersized supply duct generating high external static pressure, a cracked heat exchanger, or a misadjusted gas valve overfiring the burners. Replace the air filter first, verify external static pressure is within the rating-plate spec, inspect the blower wheel for build-up, and check manifold gas pressure against the rating plate before resetting any latched rollout switch. Never jumper a tripped limit — it is a safety device.

What does 9 flashes mean on a Tempstar furnace?

Nine flashes on a Tempstar IFC means line-voltage polarity is reversed at the furnace disconnect, or the secondary 24 V side has a wiring fault that prevents proper flame rectification. Tempstar/ICP boards use the burner ground path to rectify the flame-sense AC signal into a DC microamp current; if hot and neutral are swapped at the disconnect or sub-panel, the board cannot rectify even when there is a healthy flame. Use a multimeter on the L1 and N terminals (L1 to chassis ground should read 120 V, N to ground near 0 V); if reversed, swap the conductors at the disconnect. Polarity-reversal lockouts can also be triggered by a floating neutral upstream — verify good ground continuity from the furnace chassis back to the panel.

Are Tempstar, Heil, Comfortmaker, Day & Night, Arcoaire, and KeepRite fault codes the same?

Yes. Tempstar, Heil, Comfortmaker, Day & Night, Arcoaire, and KeepRite are all International Comfort Products (ICP) brands under Carrier Global Corporation and share the same SmartLight integrated furnace control boards, two-stage and modulating IFC platforms, defrost boards, and ION communicating wall controls. The LED flash-code chart, the F-series 2-digit codes (F2 outdoor sensor, F75 valve fault), and the ION numeric fault codes are identical across the family. Even Carrier and Bryant share much of this code book because all of them roll up under Carrier Global. Differences are limited to badging, distributor networks, and warranty terms — the underlying troubleshooting workflow is one chart for the entire ICP family.

HVAC

Tempstar error codes, decoded.

Look up any Tempstar fault code below. Each one is grounded in Tempstar's own service documentation — the meaning, the symptoms, the causes, and the steps to clear it.

Quick answer

Tempstar gas furnaces report faults via an amber Status LED on the SmartLight integrated furnace control: count the slow flashes between long pauses (1F–9F for single-digit codes, plus multi-digit codes like 11, 12, 13). Tempstar is part of International Comfort Products (ICP) under Carrier, so Heil, Comfortmaker, Day & Night, Arcoaire, and KeepRite use the identical flash-code chart.

By Octavian Ghindea

Co-founder & CTO · Reviewed May 2026

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Tempstar sits in our HVAC coverage. Every page here is transcribed from the manufacturer's manuals, not scraped from forums.

What error codes does Tempstar display?

Tap a code for the full breakdown — meaning, symptoms, causes, and fix steps.

1 Flash

Limit Switch Fault

2 Flashes

Flame Sense Fault

3 Flashes

Four Consecutive Limit Switch Faults

4 Flashes

Ignition Lockout Fault

5 Flashes

Pressure Switch Fault

6 Flashes

Status code listed in IGC LED table; specific meaning not unambiguously resolvable from the ingested text

7 Flashes

Rollout Switch Fault

8 Flashes

Internal Control Fault

9 Flashes

Temporary 1-hour auto reset (internal processor fault)

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Other HVAC brands we cover

AskWhiz documents error codes for these manufacturers in the same vertical:

Aermec Airquest Amana Belimo Bell & Gossett Bosch HVAC Braeburn Systems Bryant Carrier CIAT Climaveneta Comfortmaker