When heating or cooling fails in Sunnyvale, Santa Clara or Cupertino, the first question is not which part broke. It is whether the system is unsafe, fully down or only underperforming. A gas smell or a carbon monoxide alarm means leaving the house. No heat on a cold night or no cooling in a hot spell is an urgent repair. A rattle, one warm bedroom or a system that runs but struggles can usually wait for a regular appointment.
Three levels of HVAC emergency
Danger: leave first, then call. A rotten-egg gas smell, a carbon monoxide alarm, smoke, sparks or flames from the equipment. Do not switch lights or the thermostat on or off and do not try to restart anything. Get everyone outside and call 911 or the gas utility from there. Call us once the house has been cleared; the equipment should not run again until the cause is found. Our carbon monoxide safety guide explains where alarms belong.
Urgent: the system is down at a bad time. No heat when nights turn cold between November and March, no cooling when afternoons pass the 90s in summer, water pouring from the indoor unit, a breaker that trips every time the system starts, or a furnace that keeps locking itself out. These are the calls that get the earliest opening. Tell us when a baby, an older adult or someone ill is at home.
Can wait: the system works, just not well. A new noise while it still heats or cools, one room that never gets comfortable, a thermostat display that acts up while the equipment runs normally, or a tune-up you have put off.
What to do until the technician arrives
| Situation | Do this now | Avoid this |
|---|---|---|
| Water leaking from the indoor unit or a ceiling stain under an attic unit | Turn the system off at the thermostat, and at its breaker if water is near wiring. Catch the water. | Running the cooling “until someone comes”. |
| Outdoor unit hums but its fan does not turn | Turn the system off at the thermostat. | Pushing the fan blades with a stick to start it. |
| Breaker trips when the system starts | Reset it once. If it trips again, leave it off. | Resetting it over and over; that can ruin a motor or compressor. |
| Ice on the copper line or the indoor coil | Set cooling to Off and the fan to On so the ice melts. | Chipping the ice off the coil. |
| Furnace tries to light, then shuts down | Check the filter, the thermostat batteries and the furnace power switch. | Cycling the power again and again. |
| Burning or electrical smell, no smoke | Switch the system off at the thermostat and the breaker. | Turning it back on to see if the smell returns. |
| Cold house with a baby or older adult inside | Electric space heaters plugged straight into a wall outlet, with clear space around them. | A gas oven, range or grill for heat. |
| Hot house in a heat spell | Close blinds on the sunny side, run fans, move people to the coolest room. | Restarting an AC that hums or trips. |
How calls are triaged
Phone lines are staffed 24 hours a day, 7 days a week. The person who answers asks a few questions in a set order: is anyone in danger, is the system fully down, who is at home, and what the equipment is doing right now.
- Safety calls get instructions first: leave, call 911 or the gas utility, and call back once the house is cleared.
- No heat and no cooling get the earliest opening on the schedule.
- Leaks and electrical trips come next, after you have been told how to make the system safe.
- Systems that still run are booked for a regular visit, which can still be the same day when there is an opening.
Technicians work 8 AM to 8 PM every day, weekends included. A call at 11 PM gets advice on what is safe tonight and a place at the start of the next day’s schedule. Arrival windows depend on route load and job length; you get a confirmed window and a call ahead. For ordinary same-day scheduling, see same-day service.
Emergency speed does not skip the diagnosis
A rushed visit that swaps the most expensive part is how people pay for a compressor when the fault was a capacitor. Even on an urgent call the technician checks, in order: the thermostat call, the breaker and outdoor disconnect, the filter, the safety controls (float switch, high-limit, pressure switch, flame sensor), the electrical parts (capacitor, contactor, fuses) and visible wear. Local conditions change what comes first: heat spikes, older attic ductwork, compact equipment closets in townhomes and condos, and homes that pair a heat pump with a gas furnace.
You get the findings, the repair options and the cost factors before any work begins. Replacement parts should match the exact equipment, and the technician checks whether a manufacturer warranty still applies.
Where to go next
- No cooling during a hot spell: emergency AC repair covers the AC-specific causes.
- No heat: furnace repair or heat pump repair.
- City pages: 24/7 emergency repair in Sunnyvale, in Santa Clara and emergency services in Cupertino, plus weekend service and holiday service.
A maintenance plan catches weak capacitors, clogged drains and dirty flame sensors before they become emergencies.