Error Code RED 9 FLASHES

Goodman GMEC960803BN Error Code RED 9 FLASHES: Improper grounding or reverse polarity

TL;DR

Improper grounding or reverse polarity

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 RED 9 FLASHES Mean?

Improper grounding or reverse polarity

Common Causes

Cause	Likelihood	DIY?
115 volt hot and neutral supply to furnace reversed	Most common	✗ Call a pro →
Hot wire (door switch & L1 on control board) must read 115 volts to ground	Common	✗ Call a pro →
Neutral wire should measure 0 volts to ground	Common	✗ Call a pro →

When to Call a Professional

Contact a licensed HVAC technician if:

Basic troubleshooting did not resolve the error
You smell gas at any point during the process
You are not comfortable working around gas lines or electrical components
The unit needs a gas valve, control board, or motor replacement

Sources

Goodman GMEC96 Service Instructions Manual - Two Stage Furnace with Multi-Speed ECM Motor