3 flashes Burner failed to light or lost flame

What the control is telling you

The burner did not light, or flame was lost during the heat call.

Applies to: EL195UHNE furnaces with ignition control 103217-03 or 107163-01 (red LED)

Likely causes

• Gas off or low supply pressure
• Ignitor not glowing
• Dirty or poorly placed flame sensor
• Wrong air orifice (hard ignition)
• Poor ground
• Restricted vent/intake or plugged condensate drain

Test and repair steps

1. Confirm gas is on at the meter and both manual shut-off valves are open; supply 4.5-10.5 in. w.c. natural gas.
2. Watch a cycle 15 s pre-purge, 20 s ignitor warm-up, gas valve opens for a 4 s trial; control retries four more times.
3. Check ignitor 39-70 ohms across plug terminals 1 and 5; voltage 120 V +/-10% during warm-up.
4. Read flame signal normal 2.6 uA or more, low 2.5 uA or less, drop-out 1.1 uA (Table 7). Note: the troubleshooting flowchart uses 1.5 uA as the low limit. Clean or replace the sensor if low.
5. Check manifold pressure 3.2-3.8 in. w.c. (0-4500 ft, natural gas) and signal pressure per Table 19.
6. If ignition is rough or delayed, check the air orifice part number against Table 20 and follow the poor ignition/resonance guide.
7. Check ground and polarity at the control.

Settings for these units

• Filter sizes (filter rack kits) · Lennox EL195UHNE