9 flashes
Moderate
Goodman · HVAC Systems (AC, Furnaces & Heat Pumps)
Reversed Polarity Detected
Quick Answer
Error code 9 flashes on your Goodman HVAC Systems (AC, Furnaces & Heat Pumps) means: Reversed Polarity Detected. This is usually fixable — see the step-by-step guide below.
Likely Causes
How to Fix It
1
Use a multimeter to check voltage between hot and neutral, and hot and ground at the furnace
2
Verify the black (hot) wire is connected correctly and neutral (white) is not swapped
3
Check less than 2VAC between neutral and ground
4
Inspect the disconnect switch wiring for reversed connections
5
Contact a licensed electrician if the polarity issue is upstream of the furnace disconnect
Pro Tip
This fix requires some technical knowledge. If you're unsure about any step, consider contacting support or a qualified technician.
Parts You May Need
Wire connectors
Disconnect switch (if faulty)
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