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ALTERNATING

Lennox · ML196E Merit Series 96% AFUE Single-Stage Gas Furnace

Lennox ML196E Merit Series 96% AFUE Single-Stage Gas Furnace ALTERNATING Error Fix: Reversed Polarity on Gas Valve

The LED alternates between ON and OFF at approximately 1-second intervals. Indicates a wiring error in the gas valve circuit — the gas valve connections may be reversed. Check the gas valve wiring harness connector and the control board gas valve output terminals. Some boards also show this pattern for a shorted gas valve coil.

Medium severity2 fixes available✨ Free fix available

Quick Answer

Error ALTERNATING on the Lennox ML196E Merit Series 96% AFUE Single-Stage Gas Furnace means: Reversed Polarity on Gas Valve. The top-ranked community fix is “Test and Replace Gas Valve Coil or Control Board” (medium difficulty, ~60 min, DIY cost: $50-$80). 2 community-ranked fixes available below.

Published February 2026 · 2 fixes · furnace

Content is based on manufacturer service documentation, community repair experience, and OEM technical bulletins. Always verify with your owner's manual.Learn about our editorial standards.

When to Call a Professional

While many furnace repairs can be done safely at home, consider hiring a qualified technician if:

The repair involves electrical wiring, gas lines, or refrigerant
You've tried the top-ranked fix and the error persists
You smell gas, see sparking, or notice water leaking
The repair requires specialized tools you don't have
Your appliance is still under manufacturer warranty

Average professional repair cost for this issue: $200-$400.

Other Lennox Models with Error ALTERNATING

EL296V Elite Series 96% AFUE Two-Stage Variable Speed Gas Furnace

furnace · 2 fixes

SL280V Dave Lennox Signature Collection 80% AFUE Variable Speed Gas Furnace

furnace · 2 fixes

SL297NV Dave Lennox Signature Collection 97% AFUE Modulating Variable Speed Gas Furnace

furnace · 2 fixes

Other Lennox ML196E Merit Series 96% AFUE Single-Stage Gas Furnace Error Codes

1 FLASH

No Previous Fault Code Stored

2 fixes

10 FLASHES

Blower Motor Calibration Fault

2 fixes

11 FLASHES

Auxiliary Limit Switch Open

Inducer Motor Fault

Communicating System Fault

2 fixes

2 FLASHES

System Lockout — Retries Exhausted

2 fixes

3 FLASHES

Pressure Switch Stuck Closed

2 fixes

4 FLASHES

Pressure Switch Open — Did Not Close

2 fixes

People Also Ask About Lennox ML196E Merit Series 96% AFUE Single-Stage Gas Furnace Error ALTERNATING

What does error code ALTERNATING mean on a Lennox ML196E Merit Series 96% AFUE Single-Stage Gas Furnace?

Error code ALTERNATING on the Lennox ML196E Merit Series 96% AFUE Single-Stage Gas Furnace means: Reversed Polarity on Gas Valve. The LED alternates between ON and OFF at approximately 1-second intervals. Indicates a wiring error in the gas valve circuit — the gas valve connections may be reversed. Check the gas valve wiring harness connector and the control board gas valve output terminals. Some boards also show this pattern for a shorted gas valve coil.

How do I fix error code ALTERNATING on my Lennox ML196E Merit Series 96% AFUE Single-Stage Gas Furnace?

The most successful fix is "Test and Replace Gas Valve Coil or Control Board" (medium difficulty, ~60 minutes). Estimated DIY cost: $50-$80. HomeMD has 2 community-ranked fixes for this error.

Is error code ALTERNATING on a Lennox ML196E Merit Series 96% AFUE Single-Stage Gas Furnace serious?

This error is rated medium severity. It should be addressed soon, but your appliance may still function in a limited capacity.

Can I fix Lennox ML196E Merit Series 96% AFUE Single-Stage Gas Furnace error ALTERNATING myself?

Yes — the top-ranked community fix ("Test and Replace Gas Valve Coil or Control Board") is rated medium difficulty and takes about 60 minutes. Tools needed: Multimeter, Nut driver set, Screwdriver (Phillips).

How much does it cost to repair Lennox ML196E Merit Series 96% AFUE Single-Stage Gas Furnace error ALTERNATING?

DIY cost: $50-$80. Professional repair typically costs $200-$400. Many homeowners save money by trying the top-ranked community fix first.

What other error codes does the Lennox ML196E Merit Series 96% AFUE Single-Stage Gas Furnace have?

The Lennox ML196E Merit Series 96% AFUE Single-Stage Gas Furnace has 8 other known error codes, including: 1 FLASH (No Previous Fault Code Stored), 10 FLASHES (Blower Motor Calibration Fault), 11 FLASHES (Auxiliary Limit Switch Open), 12 FLASHES (Inducer Motor Fault), 13 FLASHES (Communicating System Fault), and 3 more.

Which other Lennox models have the ALTERNATING error?

Error code ALTERNATING also appears on 3 other Lennox models: EL296V Elite Series 96% AFUE Two-Stage Variable Speed Gas Furnace, SL280V Dave Lennox Signature Collection 80% AFUE Variable Speed Gas Furnace, SL297NV Dave Lennox Signature Collection 97% AFUE Modulating Variable Speed Gas Furnace. The fix may vary by model, so check each model's specific page for tailored repair steps.

What other error codes does the Lennox ML196E Merit Series 96% AFUE Single-Stage Gas Furnace have?

The Lennox ML196E Merit Series 96% AFUE Single-Stage Gas Furnace has 8 other known error codes:

1 FLASH — No Previous Fault Code Stored (2 fixes)
10 FLASHES — Blower Motor Calibration Fault (2 fixes)
11 FLASHES — Auxiliary Limit Switch Open (2 fixes)
12 FLASHES — Inducer Motor Fault (2 fixes)
13 FLASHES — Communicating System Fault (2 fixes)
2 FLASHES — System Lockout — Retries Exhausted (2 fixes)
3 FLASHES — Pressure Switch Stuck Closed (2 fixes)
4 FLASHES — Pressure Switch Open — Did Not Close (2 fixes)

Which other Lennox models have the ALTERNATING error?

Error code ALTERNATING also appears on 3 other Lennox models:

EL296V Elite Series 96% AFUE Two-Stage Variable Speed Gas Furnace (furnace) · 2 fixes
SL280V Dave Lennox Signature Collection 80% AFUE Variable Speed Gas Furnace (furnace) · 2 fixes
SL297NV Dave Lennox Signature Collection 97% AFUE Modulating Variable Speed Gas Furnace (furnace) · 2 fixes

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