Mitsubishi Electric makes some of the most widely installed ductless mini-splits in the country — the Mr. Slim and M-Series (MSZ/MUZ) heat pumps you see as slim wall units in homes that have no ductwork. In the mild Bay Area climate, a single ductless head is often enough to both heat and cool a room year-round, which is exactly why so many older East Bay and Peninsula homes — Eichlers, bungalows, and additions with nowhere to run ducts — add a Mitsubishi mini-split instead of tearing walls open. Triton services Mitsubishi ductless systems across the East Bay, Tri-Valley, and Peninsula, and we keep common parts on hand.
A note on Bay Area installs: because ductless is comparatively simple to hang, a lot of systems were put in by a handyman or as a DIY kit and never quite dialed in — a marginal flare connection, a low refrigerant charge, or a shortcut in the comm wiring. Those tend to surface as a fault a year or two later, and setting them right is licensed-tech work (refrigerant handling is EPA-regulated). We fix the install as much as the failure.
Systems we repair
- Single-zone mini-splits — one outdoor condenser paired to one indoor head.
- Multi-zone systems — one outdoor unit feeding several indoor heads, sometimes through a branch box.
- All head styles — wall-mounted, ceiling cassette, floor-mounted, and slim-duct/concealed units.
Every one of these is a heat pump, so it both heats and cools — and most Bay Area no-heat and no-cool calls on them come down to the same short list of faults.
Common Mitsubishi problems we fix
- E6 communication error. The indoor and outdoor units stop talking to each other — often the comm wiring, a control board, or feedback from a failing outdoor fan or compressor. It's one of the most common Mitsubishi faults we're called for.
- P5 drain / drain-pump fault. The condensate float switch or pump trips to stop an overflow, usually from a clogged drain line or a failed pump. The head stops cooling to protect your wall and floor.
- Blinking green light confusion. A blinking green (operation) LED is usually normal — it means the unit is running or receiving a signal from the remote. A blinking or steady red/orange light, or a specific blink pattern, is what actually flags a fault. We sort out which is which so you're not chasing a non-problem.
- P6 freeze / frost protection. The indoor or outdoor coil ices up and the unit shuts down to protect itself — typically a dirty filter, low airflow, or low refrigerant.
- Low refrigerant. A slow leak at a flare or coil leaves the unit running but barely heating or cooling, and it may freeze up. Finding and repairing the leak (not just topping off) is the real fix.
- Not cooling or not heating. Weak output, short-cycling, or a unit that starts and then stops — the umbrella symptoms the codes above usually explain.
Mitsubishi error & fault codes
Mitsubishi mini-splits flash fault codes on the indoor unit's LEDs and report them to the wireless or wired remote. As a rule of thumb, codes that start with E are communication or signal faults (E6 being the classic indoor-to-outdoor comm error), and P codes are protection trips (P5 drain, P6 freeze/overheat). And again — a plain blinking green light is generally normal operation, not a fault.
- Mitsubishi Mini Split Blinking Green Light — what the green LED actually means and when a blink is a real fault.
- Mini Split Not Cooling — the no-cool diagnosis behind P5, P6, and low charge.
Blink patterns and code letters can vary by model, so confirm any code against the label inside the indoor unit or the installation manual before assuming a part has failed.
What it costs in the Bay Area
Ductless repairs depend on the part and whether refrigerant is involved. In our pricing, a capacitor runs about $130–$400 and a condensate pump or drain repair $110–$350 — the common, lower-cost fixes behind a P5 or a weak fan. A control or comms board is roughly $220–$700 (the usual cure for a persistent E6 that isn't just wiring), and a refrigerant leak repair and recharge runs $180–$700. Most Mitsubishi mini-split repairs land in the $129–$900 range. We charge a diagnostic fee that's credited toward the repair when you approve the work, and you'll always get a flat, upfront price before we start.
Book Mitsubishi mini-split service
Triton repairs Mitsubishi ductless mini-splits — single-zone and multi-zone, every head style — across the East Bay, Tri-Valley, and Peninsula, including Dublin, San Mateo, Pleasanton, and Redwood City. Same-week and often same-day appointments, licensed and EPA-certified techs, and upfront pricing.
Book online or call (888) 993-5699.
Related pages
- HVAC Repair in the SF Bay Area — our full heating & cooling hub
- Mitsubishi Mini Split Blinking Green Light — normal vs. fault
- Mini Split Not Cooling — the ductless no-cool diagnosis
- Mini Split Not Heating — the winter side of the same system
- HVAC & AC Repair in Dublin — Tri-Valley service area
- HVAC & AC Repair in San Mateo — Peninsula service area
Frequently asked questions
Is a blinking green light on my Mitsubishi mini-split a problem? Usually not. On most Mitsubishi units the green (operation) LED blinks to show the unit is running or receiving a signal from the remote — that's normal. A real fault typically shows as a blinking or steady red/orange light, or a specific blink pattern that maps to a code like E6 or P5. If it's only the green light blinking and the unit is working, there's likely nothing wrong.
What does E6 mean on a Mitsubishi mini-split? E6 is a communication error between the indoor and outdoor units — they've stopped talking. It's often the interconnecting comm wiring, a control board, or feedback from a failing outdoor fan or compressor. Because it can involve the boards and the outdoor unit, E6 is a tech diagnosis rather than a DIY fix.
Why is my Mitsubishi mini-split leaking water or showing P5? P5 is a drain or drain-pump fault: the condensate float or pump has tripped to prevent an overflow, usually from a clogged drain line or a failed pump. The head stops cooling on purpose so it doesn't spill down your wall. Clearing the drain or replacing the pump resolves it.
Can you repair a DIY or handyman-installed mini-split? Yes, and it's common. A lot of ductless systems were hung by a handyman or from a DIY kit and were never quite dialed in — a weak flare, a low charge, or a comm wiring shortcut that surfaces as a fault later. We diagnose the failure and correct the install, including refrigerant work, which is EPA-licensed.
How much does Mitsubishi mini-split repair cost in the Bay Area? It depends on the part. A capacitor is about $130–$400 and a condensate pump or drain repair $110–$350; a control or comms board runs $220–$700, and a refrigerant leak repair and recharge $180–$700. Most repairs land in the $129–$900 range. The diagnostic fee is credited toward the repair when you approve the work.
Do you repair multi-zone Mitsubishi systems? Yes — we service both single-zone and multi-zone Mitsubishi setups, including systems that feed several heads through a branch box, and every head style (wall, ceiling cassette, and floor unit). We cover the East Bay, Tri-Valley, and Peninsula; call (888) 993-5699 to book.