Furnace maintenance & tune-up
The failures that ruin Januaryare visible in October.
A furnace that sat untouched since March does not tell you it has a problem until you ask it to work. We measure combustion, gas pressure and temperature rise, and inspect the heat exchanger — while there is still time to do something about what we find.
Combustion analysis Heat exchanger inspected Written report
Timing matters more here
Book it in October, not on the first cold night
Fresno furnaces sit idle for eight or nine months of the year. Dust settles on the burners and the flame sensor, bearings stiffen, and rodents find a cabinet nobody has opened since March. Almost every first-cold-night failure we attend was sitting there all summer, waiting.
There is a scheduling reality too. The first genuinely cold evening produces our heaviest call volume of the year, because the entire city switches its heat on within a few hours of each other. A tune-up in October costs exactly the same as one in December and comes with a very different wait.
The best time to find out your igniter is cracked is a mild afternoon in fall, not 10pm in January with a newborn in the house.
What is actually included
Published in full, because "multi-point inspection" tells you nothing. This is the list, and you get the readings in writing afterwards.
Combustion & safety
- Combustion analysis in the flueCarbon monoxide, oxygen and draft measured with an analyzer. This is the single most important reading on a gas furnace and the one most often skipped.
- Heat exchanger inspectionExamined visually, with a camera where access allows, and photographed. You see the images whether or not anything is wrong.
- Flue and ventingChecked for corrosion, blockage, disconnected sections and proper slope. Birds and rodents get into flues more often than people expect.
- Safety circuit testingLimit switches, rollout switches and the pressure switch tested for correct function rather than assumed working.
- Gas connections leak-checkedAll accessible joints tested at the furnace.
- CO alarm checkWe confirm you have working carbon monoxide alarms and tell you plainly if you do not.
Measured performance
- Gas pressureManifold and inlet pressure read on a manometer against the data plate. Drift here costs efficiency and shortens equipment life.
- Temperature riseMeasured at return and supply and compared to the manufacturer's stated range. Out of range points at airflow or firing rate.
- Static pressureAcross the air handler. High static shortens blower life and is the most common thing nobody checks.
- Flame sensor microampsRead against specification. A sensor can look clean and still be too weak to hold the gas valve open.
- Amp drawOn the blower and draft inducer, checked against the data plate.
- Full ignition sequence observedCall for heat, inducer, pressure switch proving, igniter, gas valve, flame proof, blower — watched end to end.
Cleaning & service
- Burners inspected and cleanedEight months of settled Valley dust affects flame quality and combustion.
- Flame sensor cleanedThe most common single cause of a furnace that lights then shuts off seconds later.
- Igniter condition and resistanceHot surface igniters fail with age and thermal cycling. Resistance tells us how close yours is.
- Blower wheel and motorInspected for dust loading and wheel imbalance, and lubricated where the motor has ports.
- Condensate drain and trapOn high-efficiency condensing furnaces, cleared and confirmed flowing. A blocked trap shuts the furnace down.
- Filter and thermostatFilter checked or replaced, thermostat operation and heat calibration verified.
The one that matters most: if a tune-up does not include combustion analysis and a heat exchanger inspection, it is a cleaning rather than a safety check. Those two items are what tell you whether the appliance burning fuel inside your house is doing it safely. More on heat exchanger inspection.
Being straight about price
Why we do not advertise a $59 furnace tune-up
You will see those ads every fall. They are not really tune-ups — they are the cost of getting a salesperson into your house, and the economics only work if something gets sold once they are inside.
On the air conditioning side that produces unnecessary refrigerant top-offs. On the heating side it produces something worse: the condemned heat exchanger. It is the highest-ticket recommendation in residential HVAC, it is nearly impossible for a homeowner to verify, and a $59 visit has every incentive to find one.
What a genuinely cheap tune-up leaves out
- Combustion analysis, because an analyzer costs money and takes time to use properly
- Actually inspecting the heat exchanger rather than gesturing at it
- Gas pressure and temperature rise, which need a manometer and twenty minutes
- Static pressure, which nobody measures unless they intend to act on it
- Any written record of the readings, because there were not any
A furnace inspection with no combustion reading is not a safety check. It is a visit.
What we actually find on a Fresno furnace
Six things that come up again and again in this valley, and every one of them is cheaper to deal with in October.
Flame sensors coated in Valley dust
By a distance the most common find. The sensor carries a tiny current to prove flame, and agricultural dust insulates it. The furnace lights, runs four seconds, and shuts down. Cleaning it takes minutes.
Igniters on the edge of failing
Hot surface igniters degrade with every thermal cycle and then break without warning, usually on the coldest night. Resistance tells us how much life is left while it is still working.
Rodent damage in the cabinet
Eight or nine months of an undisturbed warm enclosure is an invitation. Chewed low-voltage wiring and nesting material against burners are both things we find every season.
Static pressure left over from summer
The same blower moves your cold air in July. A duct or filter restriction that built up over the cooling season is still there in November, shortening blower life and pushing temperature rise out of range.
Blocked condensate traps
High-efficiency condensing furnaces produce acidic condensate that has to drain. A trap that dried out and crusted over during summer shuts the furnace down on a pressure switch fault.
Gas pressure drifted out of spec
Rarely dramatic, and it quietly costs efficiency, raises temperature rise and stresses the heat exchanger. Ten minutes with a manometer, and it is corrected.
One tune-up, or the plan?
Your furnace and your air conditioner both need annual attention. The plan covers both visits and does something to your warranty worth knowing about.
One visit
Furnace tune-up
$120 – $250
- Everything on the checklist above
- Written report with every reading
- Photos of the heat exchanger
- No obligation to anything further
Both seasons
Maintenance Plan
See plan pricing
- Two visits a year — furnace in fall, AC in spring
- Keeps your labor warranty extended for as long as we perform the annual maintenance
- Priority scheduling when the first cold snap hits
- We book you rather than waiting for you to remember
What Fresno homeowners say
★★★★★
I realized something was wrong with my AC when I got home Tuesday afternoon and noticed it wasn't blowing cold air. I called them right away, and they were able to send a technician to my Fresno home that same evening. The repair only took about 45 minutes, and everything was back to normal once the work was done.
Debbie Kram · Google review
★★★★★
Wow! Just an amazing experience! Air conditioner went out and they were able to get it fixed the same day! Wonderful crew and extremely nice. Would definitely use again.
Paige Pender · Google review
★★★★★
I had a great experience with this AC service company! From the moment I called, they were professional, responsive, and knowledgeable. The technician arrived on time, diagnosed the issue quickly, and explained everything clearly before starting the work.
Angelica Torres · Google review
Same technicians and the same measured standard on both sides of the year. Read all our Google reviews
Tune-up questions
How much is a furnace tune-up in Fresno?
Typically $120 to $250 for a single visit, depending on the system and its accessibility. That covers the full checklist on this page including combustion analysis and heat exchanger inspection, plus a written report with every reading. The maintenance plan covers both your furnace and AC visits annually. See plan details.
When should I book a furnace tune-up?
September through November, before the first cold snap. Two reasons: anything we find can be dealt with calmly rather than during a failure, and the first genuinely cold evening produces the heaviest call volume of our year. The price is identical in October and December, but the wait is not.
Do I need one if I barely use my heat?
Arguably more than someone who uses it constantly. Light use means a developing fault can sit unnoticed for years, and eight or nine months of idleness is exactly what lets dust settle on the flame sensor, stiffens bearings and gives rodents time to move in. Corrosion and heat exchanger fatigue do not depend on run hours either.
What makes your tune-up different from a $59 one?
Combustion analysis and a genuine heat exchanger inspection, which are the two items a $59 visit cannot afford to include. Those are also the only two that tell you whether an appliance burning fuel inside your house is doing it safely. You also get every reading in writing, which makes our findings checkable rather than something you have to take on trust.
Does maintenance affect my warranty?
Yes, in two ways. Most manufacturers require documented annual maintenance for parts warranty claims. And our own labor warranty starts at one year and extends up to ten years for as long as we perform the annual maintenance — if that lapses, it reverts to one year. How our warranty works.
What if you find something wrong?
We show you, in photos and readings, and give you a firm price. Nothing gets repaired without your approval, and there is no pressure to decide on the spot. If it is a safety issue we will say so clearly and explain exactly why, with the evidence in front of you rather than as an assertion. See what furnace repair involves.
How long does it take?
Usually 60 to 90 minutes for a single furnace done properly. If someone is in and out in twenty minutes, they did not measure combustion, gas pressure or static pressure, because those alone take longer than that.
Get ahead of the first cold night
Everything measured, the heat exchanger photographed, and the readings in writing.
Prices shown are typical ranges for the Fresno area and are not quotes. Labor warranty extension is conditional on annual maintenance being performed by California Heating & AC Repair; if maintenance lapses, coverage reverts to the standard one-year term. Manufacturer warranty terms vary by brand and registration status. California Heating & AC Repair is operated by Craftline Renovations, Inc. · CSLB License #999179 · Licensed and insured.