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Mitsubishi · SLZ-KF09NA 9,000 BTU 4-Way Ceiling Cassette Indoor Unit

Mitsubishi SLZ-KF09NA 9,000 BTU 4-Way Ceiling Cassette Indoor Unit EC Error Fix: Indoor Unit Address Duplication Error

Two or more indoor units in a multi-zone system have been assigned the same address. Each indoor unit connected to an MXZ multi-zone outdoor unit must have a unique address (typically set via DIP switches or rotary switch on the indoor PCB). Check and correct the address settings on all indoor units. This code only appears in multi-zone installations.

Medium severity2 fixes available✨ Free fix available

Quick Answer

Error EC on the Mitsubishi SLZ-KF09NA 9,000 BTU 4-Way Ceiling Cassette Indoor Unit means: Indoor Unit Address Duplication Error. The top-ranked community fix is “Replace Indoor Unit PCB to Resolve Address Conflicts” (medium difficulty, ~60 min, DIY cost: $10-$20). 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: $250-$350.

Other Mitsubishi Models with Error EC

MLZ-KP09NA 9,000 BTU One-Way Ceiling Cassette Indoor Unit

mini_split · 2 fixes

MSZ-EF15NA 15,000 BTU Designer Series (Kirigamine Zen) Wall-Mount Indoor Unit

mini_split · 2 fixes

MSZ-FH12NA 12,000 BTU Hyper-Heat H2i Wall-Mount Indoor Unit

mini_split · 2 fixes

MSZ-FS06NA 6,000 BTU Compact Wall-Mount Indoor Unit

mini_split · 2 fixes

MSZ-GL09NA 9,000 BTU Wall-Mount Ductless Mini-Split Indoor Unit

mini_split · 2 fixes

MSZ-GL12NA 12,000 BTU Wall-Mount Ductless Mini-Split Indoor Unit

mini_split · 2 fixes

SEZ-KD12NA 12,000 BTU Ceiling-Concealed Ducted Indoor Unit

mini_split · 2 fixes

SVZ-KP18NA 18,000 BTU Multi-Position Ducted Air Handler

mini_split · 2 fixes

Other Mitsubishi SLZ-KF09NA 9,000 BTU 4-Way Ceiling Cassette Indoor Unit Error Codes

Remote Controller PCB Error

2 fixes

Remote Controller Signal Receiving Error

2 fixes

Remote Controller Communication Error

2 fixes

Indoor Unit PCB Processor Error

2 fixes

Indoor/Outdoor Communication Error (Legacy)

2 fixes

Indoor Unit EEPROM Error

2 fixes

Indoor Fan Motor Error

2 fixes

Indoor Unit Overcurrent Protection

2 fixes

People Also Ask About Mitsubishi SLZ-KF09NA 9,000 BTU 4-Way Ceiling Cassette Indoor Unit Error EC

What does error code EC mean on a Mitsubishi SLZ-KF09NA 9,000 BTU 4-Way Ceiling Cassette Indoor Unit?

Error code EC on the Mitsubishi SLZ-KF09NA 9,000 BTU 4-Way Ceiling Cassette Indoor Unit means: Indoor Unit Address Duplication Error. Two or more indoor units in a multi-zone system have been assigned the same address. Each indoor unit connected to an MXZ multi-zone outdoor unit must have a unique address (typically set via DIP switches or rotary switch on the indoor PCB). Check and correct the address settings on all indoor units. This code only appears in multi-zone installations.

How do I fix error code EC on my Mitsubishi SLZ-KF09NA 9,000 BTU 4-Way Ceiling Cassette Indoor Unit?

The most successful fix is "Replace Indoor Unit PCB to Resolve Address Conflicts" (medium difficulty, ~60 minutes). Estimated DIY cost: $10-$20. HomeMD has 2 community-ranked fixes for this error.

Is error code EC on a Mitsubishi SLZ-KF09NA 9,000 BTU 4-Way Ceiling Cassette Indoor Unit 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 Mitsubishi SLZ-KF09NA 9,000 BTU 4-Way Ceiling Cassette Indoor Unit error EC myself?

Yes — the top-ranked community fix ("Replace Indoor Unit PCB to Resolve Address Conflicts") is rated medium difficulty and takes about 60 minutes. Tools needed: Phillips screwdriver, Multimeter, Anti-static wrist strap.

How much does it cost to repair Mitsubishi SLZ-KF09NA 9,000 BTU 4-Way Ceiling Cassette Indoor Unit error EC?

DIY cost: $10-$20. Professional repair typically costs $250-$350. Many homeowners save money by trying the top-ranked community fix first.

What other error codes does the Mitsubishi SLZ-KF09NA 9,000 BTU 4-Way Ceiling Cassette Indoor Unit have?

The Mitsubishi SLZ-KF09NA 9,000 BTU 4-Way Ceiling Cassette Indoor Unit has 8 other known error codes, including: E1 (Remote Controller PCB Error), E2 (Remote Controller Signal Receiving Error), E3 (Remote Controller Communication Error), E4 (Indoor Unit PCB Processor Error), E5 (Indoor/Outdoor Communication Error (Legacy)), and 3 more.

Which other Mitsubishi models have the EC error?

Error code EC also appears on 8 other Mitsubishi models: MLZ-KP09NA 9,000 BTU One-Way Ceiling Cassette Indoor Unit, MSZ-EF15NA 15,000 BTU Designer Series (Kirigamine Zen) Wall-Mount Indoor Unit, MSZ-FH12NA 12,000 BTU Hyper-Heat H2i Wall-Mount Indoor Unit, MSZ-FS06NA 6,000 BTU Compact Wall-Mount Indoor Unit, MSZ-GL09NA 9,000 BTU Wall-Mount Ductless Mini-Split Indoor Unit, MSZ-GL12NA 12,000 BTU Wall-Mount Ductless Mini-Split Indoor Unit, and 2 more. The fix may vary by model, so check each model's specific page for tailored repair steps.

What other error codes does the Mitsubishi SLZ-KF09NA 9,000 BTU 4-Way Ceiling Cassette Indoor Unit have?

The Mitsubishi SLZ-KF09NA 9,000 BTU 4-Way Ceiling Cassette Indoor Unit has 8 other known error codes:

E1 — Remote Controller PCB Error (2 fixes)
E2 — Remote Controller Signal Receiving Error (2 fixes)
E3 — Remote Controller Communication Error (2 fixes)
E4 — Indoor Unit PCB Processor Error (2 fixes)
E5 — Indoor/Outdoor Communication Error (Legacy) (2 fixes)
E6 — Indoor Unit EEPROM Error (2 fixes)
E7 — Indoor Fan Motor Error (2 fixes)
E8 — Indoor Unit Overcurrent Protection (2 fixes)

Which other Mitsubishi models have the EC error?

Error code EC also appears on 8 other Mitsubishi models:

MLZ-KP09NA 9,000 BTU One-Way Ceiling Cassette Indoor Unit (mini split) · 2 fixes
MSZ-EF15NA 15,000 BTU Designer Series (Kirigamine Zen) Wall-Mount Indoor Unit (mini split) · 2 fixes
MSZ-FH12NA 12,000 BTU Hyper-Heat H2i Wall-Mount Indoor Unit (mini split) · 2 fixes
MSZ-FS06NA 6,000 BTU Compact Wall-Mount Indoor Unit (mini split) · 2 fixes
MSZ-GL09NA 9,000 BTU Wall-Mount Ductless Mini-Split Indoor Unit (mini split) · 2 fixes
MSZ-GL12NA 12,000 BTU Wall-Mount Ductless Mini-Split Indoor Unit (mini split) · 2 fixes
SEZ-KD12NA 12,000 BTU Ceiling-Concealed Ducted Indoor Unit (mini split) · 2 fixes
SVZ-KP18NA 18,000 BTU Multi-Position Ducted Air Handler (mini split) · 2 fixes

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