Lennox Gas Furnace: EL195UH
Re: Flashing Code 9
Code 9 = Furnace Pressure Switch Open with Inducer On
Qty |
Possible Causes: |
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Bad Inducer Motor |
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Water in the vent (improper slope) |
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Clogged or Restricted Vent |
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Bad Pressure Switch |
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Clogged / Frozen Drain |
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Item Stuck in Inducer Motor |
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Bad Control Board |
CHECKOUT:
1. Check Control Board
- Start the furnace with a call for heat.
- Ensure that power is present on "W" by checking for 24VAC between "W" and "C".
- No Power = No Call for Heat
- Power = The Inducer motor should start within 15 seconds.
- Inducer Motor Starts → Step 2. Check Inducer
- Inducer Motor Does Not Start + Code 9 ⇒ Check for 115V power to inducer.
2. Check Inducer
- Observe and listen to the inducer motor.
- Listen for sounds of water in the vent piping (near the furnace and at the vent termination).
- If water is gurgling in the vent, look for sags or low spots in the vent piping that will hold water.
- The vent piping must have a constant slope back toward the furnace.
3. Check Pressure Switch
- Start the furnace with a call for heat.
- Check Vent Switch
- Switch Contacts
- With the wires attached to the switch, check for 24VAC between each terminal of the switch and Common.
- 24VAC On Both Sides = Switch Closed
- 24VAC On One Side Only = Open Switch ⇒ Use a pressure meter to check the pressure at the switch.
- Switch Pressure
- Remove the Pressure Switch hose from the Inducer Motor.
- Connect a pressure meter to the Inducer Motor pressure port.
- Compare actual pressure to the pressure rating on the switch.
- Pressure Near or Below Rating = Clogged or Restricted Vent
- Pressure Well Above the Rating + Open Switch = Bad Switch or Water in Switch
- Water in Switch is usually caused by a mis-run pressure switch hose.
4. Check Condensate Drainage
- Check the drain hose from the collector box.
- Make sure all drain hoses are clear and have a downward slope.
- In extreme cold conditions be cautious of Frozen Drains.