HVAC Troubleshooting
HVAC Troubleshooting Guide:
AC, Furnace & Heat Pump
Your air conditioner, furnace, or heat pump isn’t working right. Before you call a technician, check these guides — about 30% of HVAC problems have a simple fix. Written for Bay Area homeowners by licensed HVAC technicians.
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Our interactive tool walks you through symptoms step by step.
Air Conditioning Problems
The most common AC issues we see during Bay Area summers. Central AC, mini-splits, and rooftop units.
High Priority
AC Not Cooling
System runs but air isn’t cold. The most common summer call — often a simple fix like a clogged filter.
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High Priority
AC Blowing Warm Air
Fan blows but air is warm or room temperature. Thermostat, refrigerant, or compressor issue.
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High Priority
AC Freezing Up
Ice on refrigerant lines or evaporator coil. Running a frozen AC can destroy the compressor.
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Emergency
AC Won’t Turn On
No fan, no compressor, completely dead. Could be a breaker, capacitor, contactor, or thermostat.
Read guide
Furnace & Heating Problems
Common heating issues for Bay Area homes. Gas furnaces, heat pumps, and dual-fuel systems.
Emergency
Furnace Not Turning On
No heat, no fan, system completely unresponsive. Pilot light, ignitor, or control board issue.
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Schedule Service
Furnace Blowing Cold Air
Fan runs but air isn’t warm. Often a thermostat setting issue — but can also be a dirty flame sensor.
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High Priority
HVAC Short Cycling
System starts, runs a few minutes, shuts off, repeats. Stresses equipment and doubles energy bills.
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Heat Pump Problems
Increasingly common in Bay Area homes. Heat pumps have unique failure modes different from traditional AC or furnace.
High Priority
Heat Pump Not Heating
System runs in cooling mode but won’t switch to heat, or blows cool air in heating mode. Reversing valve or defrost issue.
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High Priority
Heat Pump Freezing Up
Ice on outdoor unit in winter. Normal light frost is expected — heavy ice buildup means the defrost cycle isn’t working.
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Schedule Service
Heat Pump Short Cycling
Compressor turns on and off rapidly. Low refrigerant, dirty filter, or oversized unit for the space.
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