HVAC Code Lookup

American Standard Furnace 6 Flashes

WarningShown as: 6 flashes, pause, repeat

The 115 volt AC line and neutral are reversed at the furnace, the furnace is poorly grounded, or supply voltage is too low.

Manual wording: “6 Flashes --- 115 volt AC power reversed, poor grounding or system voltage too low”

Documented for: *UD1 / *DD1 and CUB1 / CDB1 fan-assisted gas furnaces with the LED-only integrated furnace control

Likely causes, most common first

  1. 115 volt AC power reversed
  2. Poor grounding
  3. System voltage too low

What you can safely check yourself

  • Note whether the code appeared right after electrical work, a new outlet, or use of a generator
  • Check whether lights elsewhere in the house are dimming, which suggests a low-voltage supply problem

When to call a technician

Call a technician or electrician. Correcting line polarity, grounding, or a low-voltage supply is electrical work at the furnace and the panel.

A American Standard furnace throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.

Sources

Other American Standard codes