California HVAC Match
An outdoor air conditioning condenser unit positioned beside a blue-sided house at sunset.

AC Installation in San Mateo, CA

Tell us about the house, and a licensed contractor who covers San Mateo County will get in touch.

Tell us about the job

It takes about a minute.

Step 1 of 3: Equipment
An outdoor air conditioning condenser unit positioned on a concrete pad next to a blue-sided house, surrounded by green shrubs and flowering hydrangeas at sunset.

San Mateo doesn't ask much of an air conditioner

Summer afternoons here average 73°F. That's mild enough that a lot of homes get by without cooling at all, and it's part of why some houses in San Mateo County still don't have central air.

If you're putting one in, any new central air conditioner sold today has to meet a federal minimum of 14.3 SEER2, so efficiency isn't something you have to chase. The bigger question here is sizing it to a house that may only need it a handful of days a year, rather than picking a unit built for a much hotter climate.

73°F
the average summer afternoon it cools against
9 hail events
in ten years, and hail bends the fins on outdoor coils
13.4 SEER2
the federal minimum any new unit must meet
Isometric cutaway illustration of a single-story house with a dark shingled roof, showing interior rooms with ductwork and an indoor air handler connected to an outdoor condenser unit beside the building.
Your air conditioner works hardest from July through September.

NOAA nClimDiv, 1991–2020 normals

Overhead view of an outdoor AC condenser unit on a concrete pad next to a house with a dark shingle roof.

Going above the federal minimum saves little here, about $0 a year.

  • A new unit at the federal minimum, 14.3 SEER2$50 a year
  • A higher-efficiency unit$50 a year

Estimates for a typical San Mateo County home, from EIA household energy data, California fuel prices and NOAA climate normals. Your home will differ.

California requires HVAC contractors to hold a state license.

The license is issued by the Contractors State License Board, and it covers the contractor as a business, not any one job. So it stays with them across every install they do, this one included, and the board is the one keeping that record.

Because California licenses the contractor, that license is what stands behind this installation. On top of it, in most cities and counties here, putting in a new air conditioner needs a permit from the local building office, with an inspection once the work is done.

Sources: California Legislative Counsel · Contractors State License Board

What size air conditioner does my house need?
The right size depends on your home's square footage, insulation, window area, and layout, not on a rule of thumb per square foot. A contractor will run a load calculation to get this right. Sizing it wrong is the real risk here. Summer afternoons in San Mateo average 73°F, mild enough that an oversized system will short cycle even more than usual, cooling the air fast without properly pulling humidity out of it.
Should I replace the whole system or just the outdoor unit?
If the indoor coil and outdoor unit are original to each other, replacing just the outdoor unit usually is not a full fix. Manufacturers match coils and condensers for a reason, and mismatched parts can hurt efficiency and shorten the life of the new unit. A contractor can check whether your indoor coil will work with a new condenser or whether both need to go. Age matters too. If the system is old enough that the compressor is failing, the indoor coil is likely close behind it.
Do HVAC contractors in San Mateo need a state license to work on my home?
Yes. California requires HVAC contractors to hold a state license, issued by the Contractors State License Board. Ask to see the license number and check it against the CSLB's records before work starts.
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