An AC tune-up is a scheduled check of a system that still works. The technician measures how it is performing, cleans what limits its capacity and tests the parts most likely to fail on the first hot day. In Menlo Park, Atherton and Portola Valley, air conditioners often sit idle through a mild spring and then run all afternoon in a hotter spell. The tune-up is how weak parts get caught before that afternoon instead of during it.
What the visit covers
| Task | Why it matters |
|---|---|
| Rinse the outdoor coil and clear debris from the cabinet | A packed coil cannot reject heat, so capacity drops and pressures rise |
| Inspect the indoor coil and blower where accessible | Dust on the coil and blower wheel cuts airflow |
| Test the run capacitor against its rated value | A weak capacitor is a common reason a unit will not start on a hot day |
| Inspect the contactor and tighten electrical connections | Pitted contacts and loose terminals run hot and fail |
| Measure motor amp draw | High draw flags a tired motor or a strained compressor |
| Check the refrigerant charge with temperature and pressure readings | A low reading means a leak to find |
| Measure the temperature drop across the indoor coil | A quick read on overall performance |
| Flush the condensate drain and test the float switch | A clogged drain shuts the system down or leaks into a ceiling |
| Check thermostat calibration and operation | A thermostat reading a few degrees off makes the system run longer |
| Check the filter | The simplest airflow fix there is |
At the end you get the readings, what was cleaned, and anything worn along with the price to fix it. Nothing is replaced without your approval.
When to book
April and May are the easy months. Summers here are warm and dry, with highs often in the low 80s °F and some hotter spells, and the first of those spells is when tired systems quit and service calendars fill up. A spring visit gets the coil clean and the capacitor tested while there is still time to order a part. For a gas furnace, pair it with a furnace tune-up in the fall, before winter lows in the 40s.
What tune-ups turn up in these towns
Coils under shade trees. Mature trees drop leaves, blossoms and seed pods into outdoor units for much of the year. A spring rinse, and a quick clear-out after autumn leaf fall, keep the coil open.
Dust and pollen on wooded lots. In Portola Valley, outdoor coils and indoor filters load faster, and filters may need changing more often than the package suggests, especially after wildfire-smoke days. Hillside units sited down a slope also get a look at their pad and the line set’s insulation.
Old attic ducts. In older ranch homes, a tune-up often shows a healthy temperature drop at the unit but weak air at the far rooms. That points to leaky, crushed or poorly insulated ducts rather than the equipment; see duct repair.
Two systems in one house. Large Atherton homes often have a second system for an upstairs or a guest wing that runs far less than the main one. It still needs its own visit: its drain line, contactor and capacitor age whether it runs or not, and it is easy to forget until guests arrive on a hot weekend.
What a tune-up is not
It is not a repair, and it is not a refrigerant top-off. If the visit finds a worn motor, a leaking coil or a compressor drawing too much current, you get the diagnosis and the price in writing, and you decide. Some of those are better done now, some can wait, and on an older system some are a reason to start comparing replacement options. If your system has already stopped cooling, book AC repair instead.
Between visits
- Change or wash the filter as often as the system needs, more often in dusty or smoky months.
- Keep about two feet clear around the outdoor unit: trim shrubs and rake out leaves.
- If water appears near the indoor unit, switch the system off and call before it reaches a ceiling.
- Keep the visit records with the model and serial numbers. They help with warranty questions and future diagnosis, and they document the system’s age when a repair-or-replace decision comes.
Cost and maintenance plans
A tune-up typically costs $89 to $149 and takes one to two hours. If you would rather not book each season, an HVAC maintenance plan puts the yearly visits on a schedule. Before buying any plan, confirm the exact inspection tasks and measurements, the exclusions, and how renewals, cancellation, priority scheduling and repair discounts work.