York 80% Gas Furnace: TG8S
Re: Flashing Code 7 / Error Code 7
Flashing Code 7 = Lockout due to ignition retries.
► Code 7 is a Hard Lockout that disables heat operation and must be reset by cycling power to the furnace or by turning the thermostat off and back on.
Qty |
Possible Causes: |
2 |
Glow Plug Issue * |
|
Bad Blow Plug |
3 |
Dirty Flame Sensor |
|
No Gas |
|
Bad Gas Valve |
|
Bad Control Board |
CHECKOUT:
1. Glow Plug Issue
Johnson Controls has issued a service letter regarding this issue.
- On 80% furnaces with the new "Glow Stick" glow plug there has been issue with the furnace intermittently failing to ignite.
- It appears that the gas doesn't always come into contact with the glow plug.
- The solution has been to Install a Honeywell GlowFly glow plug. This igniter is a little longer and wider which provides a larger surface area for ignition.
2. Check Glow Plug
- Look for any visual cracks.
- Use a meter to test resistance of glow plug.
- No resistance = Bad Glow Plug
- Check for 120V power to the Glow Plug during an ignition sequence.
- No Power = Bad Ignition Control
- Power present but no glow = Bad Glow Plug
3. Check for Proper Ignition
- Visually inspect the burners during ignition.
- Burners should light with little or no delay from the glow plug to the flame sensor.
- Make sure flame sensor comes in good contact with the flame.
- Any delay or burners not igniting = Clogged Burners
- Burners light properly → Step 4. Check Flame Sensor
4. Check Flame Sensor
- On the multi-meter:
- Switch the test leads to "COM" and "mA".
- Set the meter on DC 200ù.
- Disconnect the wire from the flame sensor.
- Place one meter lead on the flame sensor terminal and the other on the flame sensor wire.
- Check the reading when the burners ignite.
- Minimum acceptable reading = 1 MicroAmp
- Low Reading ⇒ Clean Flame Sensor & Re-check
- Normal Reading (2 to 6 mA) but Shuts Off = Bad Ignition Control
- MOVE SENSOR LEADS BACK TO "COM" and "V" BEFORE PROCEEDING!