No heat, no cooling, strange noises, or a system that won't start — this guide covers the most common HVAC failures, what repairs cost, when you need a licensed technician, and how to hire one you can trust.
HVAC repair is the diagnosis and fix of any part of a home's heating and cooling system: the central air conditioner or heat pump, the furnace or air handler, the thermostat and controls, and the ductwork that distributes conditioned air. A technician tests electrical components, measures temperatures and pressures, checks safety controls, and inspects the heat exchanger, coils, and blower to isolate the fault.
Most repairs are completed in one visit. A diagnostic or service-call fee (typically $75–$169) covers the visit and troubleshooting, and is often credited toward the repair.
Match your symptom on our HVAC problem triage for likely causes, safe first checks, and an estimated cost range.
Thermostat or batteries, tripped breaker, clogged filter tripping a limit switch, failed igniter or flame sensor, or gas supply off.
Dirty filter, frozen coil, low refrigerant, failed capacitor, or a dirty outdoor condenser coil.
Tripped breaker, blown low-voltage fuse, failed transformer or control board, or a tripped safety switch.
Grinding or screeching signals a failing motor; banging or loud humming can mean a compressor problem — shut it off.
Musty means mold in ducts or the coil; burning means overheating wiring; rotten-egg means a possible gas leak — leave and call the utility.
Leaky or undersized ducts, a failing blower, closed registers, or equipment that's the wrong size for the home.
Installed ranges including parts and labor, before a diagnostic fee.
| Repair | Typical installed range |
|---|---|
| Thermostat replacement | $100 – $450 |
| Furnace igniter or flame sensor | $150 – $500 |
| Capacitor or contactor | $100 – $400 |
| Condensate drain / float switch | $75 – $300 |
| Blower motor | $300 – $1,100 |
| Refrigerant leak & recharge | $300 – $1,500 |
| Control board | $300 – $900 |
| Evaporator coil | $650 – $2,200 |
| Compressor or heat exchanger | $1,000 – $3,000+ |
Safe to do yourself: replace the air filter, change thermostat batteries, reset a breaker once, clear the outdoor unit of debris (power off), and empty a full condensate pan.
Call a licensed HVAC technician for anything involving:
If you smell gas or suspect carbon monoxide, leave the home immediately and call your gas utility or 911 from outside. Do not use switches or open flames.
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Most HVAC repairs fall between $150 and $1,200 including parts, labor, and a diagnostic fee. Simple fixes such as a capacitor, igniter, or flame sensor are often under $350; a compressor, heat exchanger, or control board can run well over $1,000.
If the system is more than about 12 years old and the repair costs more than half the price of a new one, or you've had repeated failures, replacement is usually the better value. Our Repair or Replace calculator weighs age, repair cost, and energy use.
Most charge $75 to $169 for the visit and troubleshooting, and many credit it toward the repair if you approve the work. After-hours and emergency visits carry a premium.
Not always. A cracked heat exchanger, gas leak, or repeated ignition lockouts can be hazardous. If you smell gas or suspect carbon monoxide, leave the home and call your gas utility or 911, then have a licensed technician inspect the system.
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