10 blinks
Easy Fix
Trane · HVAC Systems (AC, Furnaces & Heat Pumps)
Line Voltage Polarity Reversed
Quick Answer
Error code 10 blinks on your Trane HVAC Systems (AC, Furnaces & Heat Pumps) means: Line Voltage Polarity Reversed. This is usually fixable — see the step-by-step guide below.
Likely Causes
How to Fix It
1
Verify line voltage polarity at the furnace disconnect with a multimeter
2
Check that the black (hot) wire connects to the brass terminal and white (neutral) to silver
3
Test the outlet or disconnect for proper wiring with a receptacle tester
4
If the furnace is direct-wired, check the wiring at the junction box
5
Have a licensed electrician correct any reversed polarity found in the electrical panel
Pro Tip
This is a common issue that most users can resolve without specialized tools. Try the first step before moving on to more complex solutions.
Parts You May Need
Disconnect switch (if faulty)
Wire connectors
Electrical tape
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