Mitsubishi Electric service in San Mateo County
Mitsubishi mini-split acting up? We work on them.
Ductless and multi-zone Mitsubishi Electric heat pumps in homes, and CITY MULTI VRF in commercial buildings, across San Mateo and Santa Clara counties. Here is what goes wrong with them and what we do about it.
Which Mitsubishi Electric systems do you work on?
Mitsubishi Electric makes ductless mini-splits for homes: wall units, ceiling cassettes and slim ducted units on one outdoor unit, single room or multi-zone. In the US they are sold through Mitsubishi Electric Trane HVAC US, a 50/50 joint venture with Trane Technologies formed in 2018.
We repair, maintain and replace them in homes, and work on Mitsubishi Electric's commercial CITY MULTI VRF systems.
Source: Mitsubishi Electric Trane HVAC US, about us. Rules and programs change: last checked 2026-10-22.
Common Mitsubishi problems, and what we do
What owners notice, what it usually means, and how we handle it. If it smells of gas, leave the house and call your gas utility from outside.
| What you notice | What it usually means | What we do |
|---|---|---|
| Water dripping from the indoor unit | A clogged drain line, a drain line that runs uphill, or a failed condensate pump. | We clear and flush the drain, check its slope all the way out and replace a failed pump. |
| Lights blinking or a code on the indoor unit | The unit is reporting a fault. What it means depends on the model. | Note the pattern or code and the model number on the label, and tell us when you call. |
| Not cooling or heating like it used to | Dirty filters or coil, low refrigerant from a leak at a flare joint, or a fan problem. | We clean, test and leak check, and fix the leak before we recharge. |
| Heat stops for a few minutes on a cold morning | Usually the defrost cycle melting frost off the outdoor unit. It is normal. | Nothing, if the heat comes back. Call if the outdoor unit keeps icing up. |
| A musty smell when it starts | Dirt and mold growing on the indoor coil and blower wheel. | A deep clean of the indoor coil, the blower wheel and the drain pan. |
| The remote does nothing | Usually flat batteries, or something between the remote and the unit. | Try new batteries first. If it still won't respond, we find out whether the remote or the unit is at fault. |
Is your Mitsubishi system down?
Call, or book a visit online. Have the model number from the label ready if you can.
What to check before you call
A few things worth a minute before you book. If none of them fixes it, call.
- The thermostat or remote is on the right mode (Cool or Heat, not Fan) and set past the room temperature.
- The breaker for the system is on, and so is the switch beside the outdoor unit.
- The filter is clean. A clogged one can stop the cooling and freeze the coil.
- The outdoor unit is clear of leaves, plants and anything stacked against it.
- The model and serial number label is photographed: it is on the side of the outdoor unit and inside the furnace or air handler door.
Should I register my Mitsubishi system?
Mitsubishi Electric's best terms go to home systems installed by one of its Diamond Contractors and registered within 90 days of installation. Whoever installed yours, register it if it is new and check what its registration page offers; we can find the model and serial numbers for you.
Source: Mitsubishi Electric Trane HVAC US, register your product. Rules and programs change: last checked 2026-10-22.
Can you work on a Mitsubishi system someone else installed?
Yes. Who put it in doesn't matter for a repair. We work from the model and serial number on the label.
Who will be working on my system?
AD Mechanical Services Inc., owned by Adlan Cherkesbiev, under CSLB license #1155755, C-20 Warm-Air Heating, Ventilating and Air-Conditioning. We aren't connected with Mitsubishi Electric; we're the local contractor who works on it.
Tell us what it's doing. We'll take it from there.
Call and describe the problem: the noise, the smell, the room that never warms up. Or book a visit online.
