Lennox MPA012S4S Lennox Mini-Split Heat Pump System 12,000 BTU CONDENSATE DRAIN BLOCK Error Fix: Condensate Drain Blockage / Water Leak

Water leaks from indoor unit — dripping from bottom or running down wall. Drain line clogged with algae, mold, or dust. #1 mini-split maintenance issue. Clear drain by blowing compressed air from outdoor end. Flush with dilute bleach solution. Prevent future clogs by flushing every 6 months.

Medium severity2 fixes available

Quick Answer

Error CONDENSATE DRAIN BLOCK on the Lennox MPA012S4S Lennox Mini-Split Heat Pump System 12,000 BTU means: Condensate Drain Blockage / Water Leak. The top-ranked community fix is “Replace Condensate Drain Line and Inspect Drain Pan” (medium difficulty, ~60 min, DIY cost: $15-$25). 2 community-ranked fixes available below.

Published February 2026 · 2 fixes · mini split

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 mini split 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-$220.

Other Lennox MPA012S4S Lennox Mini-Split Heat Pump System 12,000 BTU Error Codes

Compressor High Pressure Protection

2 fixes

Indoor Coil Anti-Freeze Protection

2 fixes

Compressor Low Pressure Protection

2 fixes

Compressor Discharge Temperature Protection

2 fixes

Compressor Overcurrent Protection

2 fixes

Communication Error — Indoor/Outdoor

2 fixes

Indoor Fan Motor Fault

2 fixes

Indoor Ambient Temperature Sensor Fault

2 fixes

People Also Ask About Lennox MPA012S4S Lennox Mini-Split Heat Pump System 12,000 BTU Error CONDENSATE DRAIN BLOCK

What does error code CONDENSATE DRAIN BLOCK mean on a Lennox MPA012S4S Lennox Mini-Split Heat Pump System 12,000 BTU?

Error code CONDENSATE DRAIN BLOCK on the Lennox MPA012S4S Lennox Mini-Split Heat Pump System 12,000 BTU means: Condensate Drain Blockage / Water Leak. Water leaks from indoor unit — dripping from bottom or running down wall. Drain line clogged with algae, mold, or dust. #1 mini-split maintenance issue. Clear drain by blowing compressed air from outdoor end. Flush with dilute bleach solution. Prevent future clogs by flushing every 6 months.

How do I fix error code CONDENSATE DRAIN BLOCK on my Lennox MPA012S4S Lennox Mini-Split Heat Pump System 12,000 BTU?

The most successful fix is "Replace Condensate Drain Line and Inspect Drain Pan" (medium difficulty, ~60 minutes). Estimated DIY cost: $15-$25. HomeMD has 2 community-ranked fixes for this error.

Is error code CONDENSATE DRAIN BLOCK on a Lennox MPA012S4S Lennox Mini-Split Heat Pump System 12,000 BTU 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 MPA012S4S Lennox Mini-Split Heat Pump System 12,000 BTU error CONDENSATE DRAIN BLOCK myself?

Yes — the top-ranked community fix ("Replace Condensate Drain Line and Inspect Drain Pan") is rated medium difficulty and takes about 60 minutes. Tools needed: T20 Torx screwdriver, Utility knife, Bucket.

How much does it cost to repair Lennox MPA012S4S Lennox Mini-Split Heat Pump System 12,000 BTU error CONDENSATE DRAIN BLOCK?

DIY cost: $15-$25. Professional repair typically costs $150-$220. Many homeowners save money by trying the top-ranked community fix first.

What other error codes does the Lennox MPA012S4S Lennox Mini-Split Heat Pump System 12,000 BTU have?

The Lennox MPA012S4S Lennox Mini-Split Heat Pump System 12,000 BTU has 8 other known error codes, including: E1 (Compressor High Pressure Protection), E2 (Indoor Coil Anti-Freeze Protection), E3 (Compressor Low Pressure Protection), E4 (Compressor Discharge Temperature Protection), E5 (Compressor Overcurrent Protection), and 3 more.

What other error codes does the Lennox MPA012S4S Lennox Mini-Split Heat Pump System 12,000 BTU have?

The Lennox MPA012S4S Lennox Mini-Split Heat Pump System 12,000 BTU has 8 other known error codes:

E1 — Compressor High Pressure Protection (2 fixes)
E2 — Indoor Coil Anti-Freeze Protection (2 fixes)
E3 — Compressor Low Pressure Protection (2 fixes)
E4 — Compressor Discharge Temperature Protection (2 fixes)
E5 — Compressor Overcurrent Protection (2 fixes)
E6 — Communication Error — Indoor/Outdoor (2 fixes)
E8 — Indoor Fan Motor Fault (2 fixes)
F1 — Indoor Ambient Temperature Sensor Fault (2 fixes)

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