Model reference

Lennox G41UF-36B-045

Furnace

1 document12 error codes

Available documentation

Service Manual

G41UF Series Service Literature40 pg
Covers this model

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LED#1 Alternating Fast Flash / LED#2 Alternating Fast Flash on my Lennox G41UF-36B-045

M+

Sensed during ignitor warm-up period

From Service Manual 932499, p.31:

1.Access service mode to confirm the active fault code and read stored error history.

2.Measure control board supply voltage at test points. Expected: 12 VDC and 5 VDC.

3.Inspect all connectors on the main control for corrosion or backed-out pins.

Part WPW10804018

Electronic control board

Error codes (12)

CodeMeaning

LED#1 Alternating Fast Flash / LED#2 Alternating Fast FlashSensed during ignitor warm-up period only LED#1 Alternating Slow Flash / LED#2 Alternating Slow FlashWatchguard LED#1 Fast Flash / LED#2 Fast Flash (simultaneous)Normal operation, signaled when heating demand initiated at thermostat.LED#1 Fast Flash / LED#2 Slow FlashMain power polarity reversed; switch line and neutral.LED#1 OFF / LED#2 Slow FlashProve switch open, or blocked inlet/exhaust vent, or prove switch closed prior…LED#1 ON / LED#2 OFFCircuit board failure or control wired incorrectly.LED#1 ON / LED#2 ONCircuit board failure or control wired incorrectly.LED#1 ON / LED#2 Slow FlashRollout switch open, or 12-pin connector improperly attached.LED#1 Slow Flash / LED#2 Fast FlashLow flame signal; measures below 0.18 microamps.LED#1 Slow Flash / LED#2 OFFFlame sensed without gas valve energized.LED#1 Slow Flash / LED#2 ONPrimary or secondary limit switch open; limit must close within 3 minutes or…LED#1 Slow Flash / LED#2 Slow Flash (simultaneous)Power on, normal operation; also signaled during cooling and continuous fan.

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