Error Code Slow Flash
Info

American Standard AUH1B080A9H31A Error Code Slow Flash: Normal - No Call for Heat

TL;DR
Your American Standard AUH1B080A9H31A is in normal standby. The slow flash means the furnace is waiting for the thermostat to call for heat.
Disclaimer
This article is for informational purposes only and does not guarantee the accuracy or completeness of the information provided. Always turn off power and gas supply before attempting any repairs. If you smell gas, leave immediately and call your gas company. Consult a licensed HVAC technician for diagnosis and repair. Any actions taken based on this information are at your own risk.

What Does Code Slow Flash Mean?

A slowly blinking LED on your American Standard AUH1B080A9H31A's IFC board indicates normal standby operation. The furnace has full power, all safety circuits are functioning, and the system is ready and waiting for a heating demand from the thermostat. No error exists and no action is required.

The Integrated Furnace Control board communicates through LED flash patterns. The slow flash pattern specifically tells you that no thermostat call for heat is active. The room temperature is either at or above the thermostat's set point, the thermostat is in off or cooling mode, or the heating cycle has just completed and the system is between cycles.

If your home feels cold and you are wondering why the furnace is not running despite this normal status, check your thermostat settings. Confirm it is set to heat mode, the target temperature is higher than the current room temperature, and any scheduling or hold settings are not preventing the furnace from activating. Battery-powered thermostats may also stop sending signals when batteries are low.

Contact a licensed HVAC technician if any of these apply:

Sources

  1. Installer's Guide - Upflow/Horizontal, Downflow/Horizontal, Gas-Fired, Direct Vent Condensing Furnaces

✓ Verified against manufacturer service manual — March 2026