A furnace tune-up is a safety check first and a cleaning second. In San Jose a furnace may only run from late fall to early spring, but it spends the rest of the year gathering dust in an attic, garage or hall closet, and the parts that keep it safe still need a yearly look: the heat exchanger, the venting, the flame and the safety switches. Fall, before the first cold nights, is the time to book.
What the visit covers
Safety
- Combustion analysis. A probe in the flue reads carbon monoxide and oxygen while the furnace runs, which shows whether the burners are burning clean.
- Heat exchanger check. We inspect the visible surfaces for cracks, rust-through and soot, and watch the flame as the blower starts. A flame that shifts or lifts when the blower comes on is a warning sign.
- Venting and draft. Flue joints, slope and rust on standard furnaces; plastic pipe joints and the outdoor termination on condensing ones.
- Gas and safety controls. Gas connections checked for leaks, gas pressure measured, and the limit, rollout and pressure switches tested.
- Carbon monoxide readings around the furnace and at the supply registers.
Efficiency and wear
- Burners and flame sensor cleaned, igniter inspected.
- Blower wheel and motor checked, with the motor’s current draw measured.
- Temperature rise measured against the range printed on the furnace label.
- Condensate trap and drain flushed on high-efficiency furnaces.
- Filter replaced, and the thermostat run through a full heating cycle.
What we sometimes find
| Finding | Why it matters | What happens next |
|---|---|---|
| Coated flame sensor | Burners drop out mid-cycle on a cold night | Cleaned during the visit |
| Igniter with cracks or hot spots | Likely to fail soon | Replacement priced; your call |
| Clogged condensate trap | Shutdowns and water damage | Flushed during the visit |
| Dust-caked blower wheel | Low airflow, overheating, limit trips | Cleaning priced if the wheel has to come out |
| Rust or soot near the burners | Possible venting or combustion problem | More testing before the furnace runs again |
| Flame disturbed when the blower starts | Possible heat exchanger crack | Furnace kept off until it is confirmed and fixed |
Nothing is replaced without your approval, and you see the price first. If the visit turns up a fault, the next step is a furnace repair quote, not a sales pitch.
What it costs
A furnace tune-up and safety check runs $89–$199. Where yours falls depends on the type of furnace and how easy it is to reach: a condensing furnace in a tight attic takes longer than a standard one in a garage. Pair it with a spring AC tune-up, or cover both with a maintenance plan.
Records and warranties
At the end of the visit you get a written record of what was checked and measured: combustion readings, gas pressure, temperature rise and anything we recommend. Keep it with your warranty papers, since some manufacturers’ warranties ask for proof of regular professional maintenance. The readings also give next year’s visit something to compare against. A combustion number that drifts from one year to the next is often the first sign that a part is wearing, long before the furnace fails on a cold night.
Your part between visits
- Check the filter monthly during heating season. Our guide on how often to replace an HVAC filter covers sizes and types.
- Keep the furnace closet clear. Boxes stacked against a louvered door starve the burners of combustion air.
- In a garage, keep gasoline, paint and solvents well away from the furnace.
- Test your carbon monoxide alarms. California requires them in homes with gas appliances, a fireplace or an attached garage.
- Keep supply registers and the return grille open and unblocked.
If a CO alarm sounds, get everyone out and call 911 from outside. If you smell gas, leave without flipping switches, then call the gas utility or 911 from outside.
San Jose notes
- Attic furnaces with central air: the AC coil’s drain line works all summer and often joins the furnace’s own drain. It is the first thing we flush in fall.
- Blossom Valley: where the original 1970s–80s furnace is still running, the heat exchanger and venting get most of the visit’s time.
- Willow Glen: under the mature trees, leaves collect around side-wall vent terminations and roof caps. A blocked vent is a safety issue, not a nuisance.
- Cambrian: in homes around 60 years old, ducts near the furnace are often loose or leaking at the joints. We note what we see and price any duct repair separately.
- Evergreen: in tract homes with builder-grade furnaces nearing replacement age, a yearly record of combustion readings makes the repair-or-replace decision easier when the time comes.
Same-day service is available for most calls received before noon, but fall schedules fill once the nights turn cold. Booking in September or October avoids the rush.