The short answer
Most Los Altos AC breakdowns trace back to a failed capacitor or contactor, a clogged filter or condensate line, debris in the outdoor coil, or a slow refrigerant leak. We test each part, explain what failed and why, and give you a clear repair-or-replace picture before any work starts.
Air conditioners in Los Altos tend to sit idle for months and then get asked to work hard during a few warm weeks. That pattern hides small problems until the first hot afternoon, when the system hums but blows lukewarm air, or trips the breaker, or leaves a puddle near the furnace. ReliableAir HVAC Services is based in San Jose, roughly 9 miles east, and we repair central air conditioners, heat pumps and ductless units throughout ZIP 94024. Below is a practical guide to what usually goes wrong with cooling equipment here, a few checks you can do safely yourself, and how we decide whether a repair is worth it.
Check these three things before you call
Some cooling calls end with a simple fix the homeowner could have made in minutes. It is worth ruling these out first, and none of them requires opening an electrical panel or the equipment itself.
- Thermostat: confirm it is set to Cool, the setpoint is below room temperature, and the batteries are not low.
- Air filter: a filter clogged with dust and spring pollen can starve the indoor coil of air until it freezes solid.
- Breakers and the outdoor disconnect: a tripped breaker or a switch accidentally pulled during yard work will shut the condenser off.
Failures we see most often in 94024
Los Altos is a heavily treed town, and that is good for shade but hard on outdoor condensers. Leaves, seed pods and fine debris collect in the coil fins and the bottom pan over the off season. A packed coil cannot release heat, so head pressure climbs, the compressor runs hot, and cooling drops off. Cleaning the coil and straightening fins is often part of the repair.
Electrical parts are the next most common cause. Run capacitors weaken with age and heat, and a weak one can leave the fan or compressor buzzing without starting. Contactors pit and stick. Both are inexpensive parts, but diagnosing them correctly matters, because replacing a capacitor without asking why it failed can mask a struggling compressor motor.
Inside, a clogged condensate line is a frequent culprit, particularly where the furnace and coil sit in an attic. Algae and dust build up in the drain, water backs into the pan, and a float switch shuts the system off. Clearing the line, flushing it and checking the slope prevents a repeat.
Refrigerant leaks and older equipment
If your system needs refrigerant, it has a leak. Air conditioners do not consume refrigerant, so simply adding more is a temporary measure that hides the real problem. We use electronic detection and pressure testing to locate the leak, which is often at the indoor coil, a flare fitting or a service valve.
Older systems that use R-22 refrigerant are a special case. That refrigerant is no longer produced, so recharging is limited to reclaimed supply. For an R-22 unit with a significant coil leak, we will explain plainly that a repair may not be the sensible spend, and walk through options, including a heat pump that would handle both cooling and heating.
Ductwork that makes a working AC feel broken
Sometimes the equipment is fine and the house still feels warm. Many Los Altos homes have ductwork that has been in the attic or crawlspace for decades. Joints separate, flexible ducts get crushed during other projects, and insulation wraps deteriorate. Cooled air ends up in the attic instead of the bedroom.
During a repair visit we measure supply temperatures at several registers and compare them with the temperature at the coil. A large difference points to duct losses. Sealing the worst connections or replacing a collapsed run can restore comfort in rooms that never seemed to cool properly.
Repair or replace: how we frame it
We do not push replacement on a system that has years left in it. The factors we weigh with you are the age of the equipment, the type of refrigerant, the condition of the compressor and coils, and whether the same part has failed before. If replacement does make sense, it is worth knowing that the Bay Area Air District appliance rules do not force anyone to replace working equipment, and that heat pumps are the direction those rules point for heating. A new heat pump installed today is not eligible for the federal 25C credit, which ended for systems placed in service after 2025, but BayREN and local clean energy providers may offer incentives, which we verify before quoting.
We also handle cooling repairs in nearby Mountain View, Palo Alto, Sunnyvale, Cupertino and Los Altos Hills.
More services in Los Altos
- Heating Repair in Los Altos
- Heat Pump Installation in Los Altos
- AC Installation in Los Altos
- Furnace Repair in Los Altos