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CONDENSATE DRAIN CLOG

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

Lennox SL297NV Dave Lennox Signature Collection 97% AFUE Modulating Variable Speed Gas Furnace CONDENSATE DRAIN CLOG Error Fix: Condensate Drain Clogged (90%+ AFUE)

Condensate drain system is blocked, causing water to back up inside the furnace. Applies to EL296V, SL297NV, and ML196E (90%+ AFUE condensing furnaces). These furnaces produce acidic condensate (pH 3–5). Symptoms: water leaking from cabinet, pressure switch tripping (4 FLASHES), water pooling around furnace base. Clear the trap and drain line, flush with dilute bleach solution. Does NOT apply to SL280V (80% AFUE non-condensing).

Medium severity2 fixes available

Quick Answer

Error CONDENSATE DRAIN CLOG on the Lennox SL297NV Dave Lennox Signature Collection 97% AFUE Modulating Variable Speed Gas Furnace means: Condensate Drain Clogged (90%+ AFUE). The top-ranked community fix is “Replace the Condensate Drain Trap and Inspect Drain Line” (medium difficulty, ~45 min, DIY cost: $10-$20). 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: $150-$250.

Other Lennox Models with Error CONDENSATE DRAIN CLOG

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

furnace · 2 fixes

ML196E Merit Series 96% AFUE Single-Stage Gas Furnace

furnace · 2 fixes

Other Lennox SL297NV Dave Lennox Signature Collection 97% AFUE Modulating Variable Speed 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 SL297NV Dave Lennox Signature Collection 97% AFUE Modulating Variable Speed Gas Furnace Error CONDENSATE DRAIN CLOG

What does error code CONDENSATE DRAIN CLOG mean on a Lennox SL297NV Dave Lennox Signature Collection 97% AFUE Modulating Variable Speed Gas Furnace?

Error code CONDENSATE DRAIN CLOG on the Lennox SL297NV Dave Lennox Signature Collection 97% AFUE Modulating Variable Speed Gas Furnace means: Condensate Drain Clogged (90%+ AFUE). Condensate drain system is blocked, causing water to back up inside the furnace. Applies to EL296V, SL297NV, and ML196E (90%+ AFUE condensing furnaces). These furnaces produce acidic condensate (pH 3–5). Symptoms: water leaking from cabinet, pressure switch tripping (4 FLASHES), water pooling around furnace base. Clear the trap and drain line, flush with dilute bleach solution. Does NOT apply to SL280V (80% AFUE non-condensing).

How do I fix error code CONDENSATE DRAIN CLOG on my Lennox SL297NV Dave Lennox Signature Collection 97% AFUE Modulating Variable Speed Gas Furnace?

The most successful fix is "Replace the Condensate Drain Trap and Inspect Drain Line" (medium difficulty, ~45 minutes). Estimated DIY cost: $10-$20. HomeMD has 2 community-ranked fixes for this error.

Is error code CONDENSATE DRAIN CLOG on a Lennox SL297NV Dave Lennox Signature Collection 97% AFUE Modulating Variable Speed 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 SL297NV Dave Lennox Signature Collection 97% AFUE Modulating Variable Speed Gas Furnace error CONDENSATE DRAIN CLOG myself?

Yes — the top-ranked community fix ("Replace the Condensate Drain Trap and Inspect Drain Line") is rated medium difficulty and takes about 45 minutes. Tools needed: T20 Torx screwdriver, Phillips screwdriver, Bucket.

How much does it cost to repair Lennox SL297NV Dave Lennox Signature Collection 97% AFUE Modulating Variable Speed Gas Furnace error CONDENSATE DRAIN CLOG?

DIY cost: $10-$20. Professional repair typically costs $150-$250. Many homeowners save money by trying the top-ranked community fix first.

What other error codes does the Lennox SL297NV Dave Lennox Signature Collection 97% AFUE Modulating Variable Speed Gas Furnace have?

The Lennox SL297NV Dave Lennox Signature Collection 97% AFUE Modulating Variable Speed 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 CONDENSATE DRAIN CLOG error?

Error code CONDENSATE DRAIN CLOG also appears on 2 other Lennox models: EL296V Elite Series 96% AFUE Two-Stage Variable Speed Gas Furnace, ML196E Merit Series 96% AFUE Single-Stage 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 SL297NV Dave Lennox Signature Collection 97% AFUE Modulating Variable Speed Gas Furnace have?

The Lennox SL297NV Dave Lennox Signature Collection 97% AFUE Modulating Variable Speed 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 CONDENSATE DRAIN CLOG error?

Error code CONDENSATE DRAIN CLOG also appears on 2 other Lennox models:

EL296V Elite Series 96% AFUE Two-Stage Variable Speed Gas Furnace (furnace) · 2 fixes
ML196E Merit Series 96% AFUE Single-Stage Gas Furnace (furnace) · 2 fixes

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