HVAC problems rarely happen at a convenient time. An air conditioner quits on the hottest afternoon of the year, a furnace fails on a cold, damp night. Knowing what is going on helps you decide what to do next. The guides below cover the problems we see most often in homes in Novato, San Rafael, San Anselmo, Larkspur and Sausalito, sorted by type and by how soon they need attention. Each one explains the symptoms, the likely causes, the checks you can safely try and when to call.
How urgent is it?
- Urgent: the system has stopped heating or cooling when you need it, or there is a safety sign such as a gas smell, a burning smell or water coming through a ceiling.
- Schedule soon: comfort problems that get worse with time, such as weak airflow or rooms that never reach the setting.
- Monitor: slow changes, such as rising bills or a new sound, that are worth tracking and mentioning at the next visit.
Cooling problems
| Guide | What you notice | Urgency |
|---|---|---|
| AC not cooling | The system runs but the house stays warm | Urgent in hot weather |
| AC blowing warm air | Vents blow room-temperature or warm air | Urgent |
| Frozen AC coils | Ice on the indoor coil, the copper line or the outdoor unit | Turn cooling off, then call |
| Refrigerant leak | Cooling fades over weeks, sometimes with ice or a hiss | Schedule soon |
Heating problems
Furnace not heating covers a furnace that runs but puts out no heat, burners that light and go out, and a blower that runs cold. With cool, damp winters, heating runs for much of the year here, and the first cold night after a long idle stretch is when weak igniters and dirty flame sensors show up.
Airflow and comfort
- Uneven temperatures: some rooms too hot, others too cold. Often ducts in a tight crawlspace or an addition the system was never sized for.
- Poor airflow: weak air from the vents, from a clogged filter to a failing blower.
Bills, noises and controls
- High energy bills: costs climbing without a clear reason.
- Strange HVAC noises: banging, squealing, rattling or clanking.
- Thermostat not working: a blank or unresponsive display.
- HVAC short cycling: the system turns on and off every few minutes.
When to call a professional
Some problems have simple fixes, such as a dirty filter, dead thermostat batteries or a tripped breaker. Stop there if it does not help. Refrigerant, gas connections and electrical parts need a technician with the right tools, and anything with a gas smell needs you out of the house first. When you call, you get an itemized price after the diagnosis and before any work starts. For a failure that cannot wait, see emergency HVAC.