York Gas Furnace: PT9
Re: Flashing Code 9
Code 9 = Indicates reversed line voltage polarity, reversed low voltage wiring, or Grounding problem
| Qty |
Possible Causes: |
| 1 |
Loose Ground |
|
Missing Ground |
|
Reversed Line Voltage ("Hot" on white) |
|
Reversed Low Voltage |
|
Loose "Neutral" Wire |
| 1 |
Bad Control Board |
CHECKOUT:
1. Check Grounding & Power
- Inspect the incoming power for a connected Ground wire.
- Check voltage from "Neutral" to the grounded furnace cabinet.
- Any voltage reading = Improper Ground or Reversed Line Voltage
- Check voltage from "Hot" to the grounded furnace cabinet.
- No Voltage = Reversed Line Voltage
- Partial Voltage = Improper Ground
2. Check Neutral
- After confirming a good "Ground", check voltage from "Hot" to the grounded furnace cabinet.
- Compare voltage from "Hot" to "Neutral".
- Low voltage between "Hot" and "Neutral" = Loose "Neutral" Wire
- Look for a loose or burnt Neutral connection between the furnace and power source.
3. Check Low Voltage Polarity
- Turn off power to the furnace.
- Try reversing the two secondary (low voltage) wires at the furnace transformer.
- Re-apply power to the furnace.
- Still Code 9 ⇒ Suspect a Bad Control Board