You've seen the ads: "$79 furnace tune-up!" or "$99 AC tune-up!" But what does that actually mean? What does a technician do for an hour at your house, and is it worth it?

At Snohomish Furnace & Air, we believe in transparency. Here's exactly what our technicians check, test, and adjust during a standard tune-up — and why each item matters.

Furnace Tune-Up Checklist

A thorough furnace tune-up takes 60–90 minutes and covers these items:

Safety Checks

• Heat exchanger inspection — We visually inspect the heat exchanger for cracks or corrosion. A cracked heat exchanger can allow carbon monoxide into your home. This is the most important safety check we perform.
• Flue and venting inspection — We check that exhaust gases are properly venting to the outside and that there are no blockages or leaks in the flue.
• Gas pressure test — We verify that gas pressure at the furnace is within the manufacturer's specified range.
• Carbon monoxide test — We test CO levels in the flue gases and at the supply registers.
• Safety control testing — We test the high-limit switch, pressure switches, and rollout switches to verify they function correctly.

Combustion and Efficiency

• Burner inspection and cleaning — We inspect the burners for proper flame pattern and clean any carbon buildup that reduces efficiency.
• Ignitor inspection — We check the hot surface ignitor for cracks or wear. A failing ignitor is one of the most common causes of no-heat calls.
• Flame sensor cleaning — The flame sensor tells the furnace that the burners are lit. A dirty sensor causes nuisance shutdowns. We clean it with fine steel wool.
• Heat exchanger cleaning — We remove any debris from the heat exchanger surfaces.
• Combustion analysis — On request, we can perform a combustion efficiency test to verify the furnace is burning fuel optimally.

Electrical and Controls

• Control board inspection — We check for error codes, burnt components, or signs of electrical issues.
• Wiring inspection — We check all electrical connections for tightness and signs of heat damage.
• Thermostat calibration — We verify the thermostat is reading accurately and communicating correctly with the furnace.
• Blower motor inspection — We check the blower motor for proper operation, unusual noise, and amp draw.

Airflow and Filtration

• Air filter check — We inspect the filter and replace it if you've provided a new one (or recommend replacement if it's dirty).
• Blower wheel inspection — A dirty blower wheel reduces airflow and efficiency. We inspect it and clean it if needed.
• Supply and return air temperature measurement — We measure the temperature rise across the heat exchanger to verify it's within spec.

Final Steps

• System startup and operation test — We run the furnace through a complete heating cycle and verify normal operation.
• Written report — We document everything we found and any recommendations.

AC Tune-Up Checklist

An AC tune-up is typically performed in spring before cooling season. It covers:

Outdoor Unit (Condenser)

• Coil cleaning — We clean the condenser coils with coil cleaner and a gentle rinse. Dirty coils reduce efficiency and can cause the compressor to overheat.
• Fan blade inspection — We check the condenser fan blades for damage and verify proper rotation.
• Electrical connections — We check and tighten all electrical connections.
• Capacitor test — Capacitors are one of the most common AC failure points. We test them and flag any that are weakening.
• Contactor inspection — We inspect the contactor for pitting or burning.
• Refrigerant pressure check — We check refrigerant pressures to verify the system is properly charged. (Adding refrigerant is a separate charge if needed.)

Indoor Unit (Air Handler/Evaporator)

• Evaporator coil inspection — We inspect the evaporator coil for dirt buildup and signs of icing.
• Condensate drain inspection — We check the condensate drain line for blockages and flush it if needed. A clogged drain can cause water damage.
• Blower motor and wheel inspection — Same as the furnace tune-up.
• Air filter check — We inspect and replace if needed.

System Performance

• Temperature split measurement — We measure the temperature difference between supply and return air to verify the system is cooling properly.
• Thermostat verification — We verify the thermostat is communicating correctly with the AC.
• Full cooling cycle test — We run the system through a complete cooling cycle.

What a Tune-Up Is NOT

A tune-up is a preventive maintenance service. It is not:

• A repair service (repairs are quoted separately)
• A refrigerant recharge (adding refrigerant is a separate charge)
• A duct cleaning
• A guarantee against future breakdowns

If we find a problem during the tune-up, we'll tell you what it is, what it will cost to fix, and whether it needs immediate attention or can wait.

Is a Tune-Up Worth It?

Yes — for most homeowners, annual maintenance pays for itself. Here's why:

It catches small problems before they become expensive ones. A $15 flame sensor cleaning prevents a $300 no-heat service call. A $50 capacitor replacement prevents a $1,500 compressor failure.

It maintains efficiency. A dirty furnace or AC works harder and uses more energy. Regular maintenance keeps your system running at rated efficiency.

It extends equipment life. Well-maintained systems last longer. A furnace that gets annual tune-ups routinely lasts 18–22 years. One that's ignored may fail at 12–15 years.

It protects your warranty. Many equipment warranties require documented annual maintenance.

Schedule Your Tune-Up

We offer furnace tune-ups starting at $79 and AC tune-ups starting at $79. Combination furnace + AC tune-ups are available at a discount.

Call 425-610-6635 or schedule online. We serve Snohomish, Lake Stevens, Everett, Marysville, Monroe, and surrounding communities — 7 days a week.