Most heating and cooling problems start with one of a few things: the thermostat, the air filter, a tripped breaker, a blocked drain or a worn part like a capacitor. This troubleshooter walks you through the safe checks for your symptom and tells you when it's time for a technician. If you smell gas or a carbon monoxide alarm goes off, leave the house first and call 911 from outside.
Five checks that fix a lot of problems
Before you book, try these. They're safe for any homeowner and solve many "it's broken" calls outright.
- Thermostat. HEAT or COOL, a few degrees past room temperature, fan on AUTO, and fresh batteries if it uses them.
- Air filter. A clogged filter can freeze an AC coil or make a furnace shut itself off to avoid overheating.
- Breakers and switches. The indoor and outdoor units usually have separate breakers, and many furnaces have a power switch that looks like a light switch. Reset a tripped breaker once.
- Drain pan and float switch. Water in the pan under the indoor unit can trip a float switch that shuts the system off.
- Outdoor unit. Clear leaves, weeds and anything stored against it, and never cover or box it in.
When to stop and call right away
If you smell gas (a rotten-egg smell), leave the house now. From outside, call 911 or SDG&E at 1-800-611-7343. In Temecula and Murrieta, call 911 or SoCalGas; on propane, your propane supplier. If a carbon monoxide alarm sounds, get everyone into fresh air and call 911.
- A breaker trips a second time.
- You smell burning or see smoke. Turn the system off at the thermostat and the breaker.
- The outdoor unit hums but its fan won't spin.
- Ice comes back within a day or two of thawing.
- Water reaches a ceiling, or is near wiring or outlets.
Don't open panels on the indoor or outdoor unit. Both have high-voltage parts, and capacitors can hold a charge after the power is off. Refrigerant work also needs an EPA-certified technician. When you're ready, call (760) 728-8716 or book online and tell us what the troubleshooter found; it saves time on the visit.
Guides for specific problems
Common HVAC problems
The issues we see most in Fallbrook homes, and the fixes.
Furnace not working
Safe checks for a furnace that won't start or blows cold.
Heat pump not heating
What a normal defrost cycle looks like, and what isn't normal.
Ice on the AC lines
How to thaw a frozen coil and find out why it froze.
AC leaking water
Drain lines, float switches and drain pans explained.
AC turning on and off
Why short cycling happens and what it costs you.
Frequently asked questions
What should I check first when my AC or furnace stops working?
Start with the thermostat (right mode, a setpoint past room temperature, fresh batteries), then the air filter, then the breakers for the indoor and outdoor units. Reset a tripped breaker once; if it trips again, leave it off and call. These checks solve a surprising number of calls.
When should I stop troubleshooting and call a technician?
Stop and call if a breaker trips more than once, you smell burning, the outdoor unit hums but its fan won't spin, ice keeps coming back, or water reaches a ceiling or wiring. Don't open panels on either unit: capacitors can hold a dangerous charge even with the power off.
What should I do if I smell gas?
Leave the house right away without touching switches, the thermostat or appliances. From outside, call 911 or SDG&E's gas emergency line at 1-800-611-7343 (SoCalGas in Temecula and Murrieta, or your propane supplier). Don't go back in until they say it's safe.