When an air conditioner in Menlo Park stops cooling, the cause is usually on a short list: the thermostat signal, a clogged filter or another airflow problem, a dirty outdoor coil, a weak capacitor or other electrical part, or a refrigerant leak. A furnace that stops heating usually points to ignition, flame sensing, a safety switch or airflow. Those get checked before anyone talks about new equipment. And when a system does need replacing, correct sizing and the condition of the ducts matter more than the brand on the box.
Menlo Park HVAC Pros is a local HVAC company that repairs, maintains and installs heating and cooling systems for homes in Menlo Park, Atherton and Portola Valley. Call (650) 567-5385 or use the Request service button. Same-day service is available, and urgent no-heat, no-cooling, gas-odor and breaker-trip calls are taken 24/7.
Diagnosis first, then a recommendation
A part that looks failed is often reacting to something else. An outdoor unit that will not start may only need a capacitor. A bedroom that never cools may sit at the end of a crushed or disconnected duct rather than under an undersized unit. A furnace that lights and then shuts off may be protecting itself from a clogged filter. So a visit starts with the symptom, the equipment and the house:
- Thermostat and controls: the mode and settings, the wiring, and whether the call for heat or cooling actually reaches the equipment.
- Airflow: the filter, the return grilles, the blower and the temperature change across the indoor coil or furnace.
- Electrical parts: capacitors, contactors, fuses, the outdoor disconnect and how much current the motors draw.
- The outdoor unit: coil condition, the fan, and refrigerant symptoms such as ice on the copper lines.
- Gas equipment safety: ignition, flame sensing, pressure and limit switches, and venting.
- Age and history: how old the system is, what has already been replaced, and the ducts it depends on.
Before you approve a larger repair or an installation, you get the diagnosis, parts, labor and options in writing. One failed part on a system that otherwise runs well is usually worth repairing. Replacement becomes the realistic choice when an older system needs a major component, has needed repeated repairs, or would still be held back by its ducts or electrical service after a fix.
Three towns, three kinds of houses
Menlo Park (94025). Many homes here are more than 50 years old: mid-century ranch houses and older bungalows in neighborhoods such as Belle Haven, Linfield Oaks, The Willows, Allied Arts and Downtown Menlo Park, often with original or patched ductwork and uneven insulation. Mature street trees shade some houses all afternoon while others take the full sun, and newer rebuilds and heat-pump retrofits stand on the same blocks. Summers are warm and dry, with highs often in the low 80s and some hotter spells; winter nights drop into the 40s. More on our Menlo Park page.
Atherton (94027). Large lots and large homes, from mid-20th-century ranch houses to big newer houses in areas such as Lindenwood and West Atherton. Many run two or more systems or zones, with long duct runs and equipment in attics, basements or side yards. A complaint about “the AC” often turns out to be one zone or one long run, which is why the whole layout gets looked at. See HVAC services in Atherton.
Portola Valley (94028). A wooded foothill town of spread-out homes on hillside lots, including Westridge and Blue Oaks. Nights are cooler than on the bay side and summer afternoons get hot, so one system has to cover both. Where the outdoor unit can sit on a slope and stay quiet, long refrigerant and electrical runs, dust and pollen, and wildfire-smoke days all shape the work. See HVAC services in Portola Valley.
We also work in West Menlo Park and Ladera, next door to these towns.
What is going on, and where to start
| What you notice | What it often is | Where to start |
|---|---|---|
| The AC runs, but the house stays warm | Airflow restriction, dirty outdoor coil, weak capacitor or refrigerant leak | AC repair |
| The outdoor unit hums, but its fan does not spin | Failed capacitor or fan motor | AC repair |
| A breaker trips when the system starts, or there is a burning smell | Shorted motor, failing compressor or a wiring fault | Switch it off, then emergency AC repair |
| The furnace will not light, or lights and shuts off | Igniter, flame sensor, pressure or limit switch, clogged filter | Furnace repair |
| No heat at all on a cold night | Ignition lockout, failed blower motor or control board | Emergency heating repair |
| The heat pump ices over or never stops running | Defrost control or sensor, low airflow, low refrigerant | Heat pump repair |
| One room is always too hot or too cold | Leaking, crushed or disconnected duct | Duct repair |
| Dust, stale air or a smoke smell indoors | Weak filtration, or leaky ducts pulling in attic or crawlspace air | Indoor air quality |
| An older system that keeps needing repairs | Worn major components | AC, furnace or heat pump installation |
| An addition or a room the ducts never reached | No duct path to the room | Ductless mini-split installation |
| A blank thermostat, or one you want to replace | Power, wiring or compatibility | Thermostat installation |
If you smell gas, do not flip switches. Leave the house and call the gas utility or 911 from outside. If a carbon monoxide alarm sounds, get everyone outside and call 911. Our emergency HVAC tips cover what is safe to check while you wait.
How a visit works
- Call or request service. Describe what the system is doing. The system type, its rough age and a photo of the data plate on the indoor or outdoor unit help the technician arrive prepared. Same-day service is available; the schedule decides how soon someone can come.
- Diagnosis. The technician checks the symptom, the equipment and the house before recommending a part or a new system.
- Written next steps. For a larger repair or an installation, the diagnosis, parts, labor and options are put in writing so you can decide without pressure.
- The work. Only what you approved gets done.
Planning a new system or keeping one running
Estimates for new and replacement systems are free. AC installation adds or replaces cooling on an existing furnace and duct system; central air installation is for a house with no ducts or ducts too worn to reuse; a heat pump heats and cools with one system. Before you choose, see which programs may help on our rebates page.
To keep a system out of trouble, book an AC tune-up in spring and a furnace tune-up in fall, or cover both with an HVAC maintenance plan.
Why homeowners call us
- Diagnosis before recommendations, and written next steps before larger work.
- Urgent calls taken 24/7, and an office that is open every day of the week.
- An independent company that works on the major brands, including Carrier, Trane, Lennox, Daikin and Mitsubishi Electric. We are not affiliated with any manufacturer; the full list is on the brands page.
- A 4.9 average rating across 178 reviews.
More about how we work is on the about page.
Questions and guides
Hours, estimates, emergency calls and what to have ready are answered in the FAQ. The blog covers the signs your ductwork needs attention and how smart thermostats compare.