Lennox CBX27UH Lennox Variable Speed Air Handler DRAIN PAN OVERFLOW Error Fix: Condensate Drain Pan Overflow

Air handler drain pan has overflowed due to clogged primary drain line. Symptoms: water leaking, ceiling staining (if in attic), secondary drain dripping. Clear primary drain with wet/dry vacuum or compressed air. Install a condensate drain pan safety switch to prevent water damage.

Medium severity2 fixes available

Quick Answer

Error DRAIN PAN OVERFLOW on the Lennox CBX27UH Lennox Variable Speed Air Handler means: Condensate Drain Pan Overflow. The top-ranked community fix is “Install a Condensate Drain Pan Safety Switch” (medium difficulty, ~60 min, DIY cost: $15-$30). 2 community-ranked fixes available below.

Published February 2026 · 2 fixes · air handler

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 air handler 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 CBX27UH Lennox Variable Speed Air Handler Error Codes

AH BLOWER MOTOR FAIL

Blower Motor Failure

2 fixes

EVAPORATOR COIL DIRTY

Indoor Coil Dirty / Restricted

2 fixes

FLASHING GREEN

Normal — Blower Running

2 fixes

FLASHING YELLOW

High Limit — Electric Heat

No Power

Electric Heat Strip Sequencer Failure

Normal — Standby

Control Board Fault

People Also Ask About Lennox CBX27UH Lennox Variable Speed Air Handler Error DRAIN PAN OVERFLOW

What does error code DRAIN PAN OVERFLOW mean on a Lennox CBX27UH Lennox Variable Speed Air Handler?

Error code DRAIN PAN OVERFLOW on the Lennox CBX27UH Lennox Variable Speed Air Handler means: Condensate Drain Pan Overflow. Air handler drain pan has overflowed due to clogged primary drain line. Symptoms: water leaking, ceiling staining (if in attic), secondary drain dripping. Clear primary drain with wet/dry vacuum or compressed air. Install a condensate drain pan safety switch to prevent water damage.

How do I fix error code DRAIN PAN OVERFLOW on my Lennox CBX27UH Lennox Variable Speed Air Handler?

The most successful fix is "Install a Condensate Drain Pan Safety Switch" (medium difficulty, ~60 minutes). Estimated DIY cost: $15-$30. HomeMD has 2 community-ranked fixes for this error.

Is error code DRAIN PAN OVERFLOW on a Lennox CBX27UH Lennox Variable Speed Air Handler 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 CBX27UH Lennox Variable Speed Air Handler error DRAIN PAN OVERFLOW myself?

Yes — the top-ranked community fix ("Install a Condensate Drain Pan Safety Switch") is rated medium difficulty and takes about 60 minutes. Tools needed: Multimeter, Wire strippers, Phillips screwdriver, Drill with bits.

How much does it cost to repair Lennox CBX27UH Lennox Variable Speed Air Handler error DRAIN PAN OVERFLOW?

DIY cost: $15-$30. 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 CBX27UH Lennox Variable Speed Air Handler have?

The Lennox CBX27UH Lennox Variable Speed Air Handler has 8 other known error codes, including: AH BLOWER MOTOR FAIL (Blower Motor Failure), EVAPORATOR COIL DIRTY (Indoor Coil Dirty / Restricted), FLASHING GREEN (Normal — Blower Running), FLASHING YELLOW (High Limit — Electric Heat), NO LIGHT (No Power), and 3 more.

What other error codes does the Lennox CBX27UH Lennox Variable Speed Air Handler have?

The Lennox CBX27UH Lennox Variable Speed Air Handler has 8 other known error codes:

AH BLOWER MOTOR FAIL — Blower Motor Failure (2 fixes)
EVAPORATOR COIL DIRTY — Indoor Coil Dirty / Restricted (2 fixes)
FLASHING GREEN — Normal — Blower Running (2 fixes)
FLASHING YELLOW — High Limit — Electric Heat (2 fixes)
NO LIGHT — No Power (2 fixes)
SEQUENCER FAILURE — Electric Heat Strip Sequencer Failure (2 fixes)
SOLID GREEN — Normal — Standby (2 fixes)
SOLID RED — Control Board Fault (2 fixes)

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