What does a furnace tune-up include?

A tune-up is an inspection. A tech looks at your system, measures how it is running, cleans a few parts, and tells you what they found. Fixing what they found is not part of it. That is a separate job with its own price, and you have to agree to it first.

ENERGY STAR lists what a typical check-up should cover: the thermostat settings, the electrical connections, voltage and current on the motors, the moving parts, the condensate drain, and the controls, including the start and stop cycle. For heating it adds the gas or oil connections, the gas pressure, the burner combustion, and the heat exchanger. ENERGY STAR also says to book it before the season starts, so the heating system in the fall and the cooling system in the spring.

That is the easy half of the question. The hard half is what happens when the tech comes back upstairs with a list of quotes, and the rest of this post is about that.

Why two tune-ups can be completely different

Nobody owns the word. One company’s tune-up is an hour of measuring. Another company’s tune-up is ten minutes and a sticker.

ACCA, the trade group for heating and cooling contractors, says there was no way to tell whether all the different “seasonal tune-ups,” “clean and checks,” and “maintenance services” were even the same thing. So they wrote a standard, ANSI/ACCA 4 QM, that sets the smallest list of tasks a maintenance visit should cover.

One idea in that standard is worth more to you than the whole task list. It splits the visit in two:

• Inspection tasks. Looking, testing, and measuring. This is the tune-up you paid for.
• Recommended corrective actions. Fixing what the inspection turned up. These cost extra, on purpose.

So a quote at the end of a tune-up is not proof that someone is cheating you. It is how the visit is built. The standard says the contractor has to tell you what they found, what they fixed, what they recommend, and the price of each thing they recommend. It also says you need to know which items were part of the maintenance and which ones need your go-ahead.

Ask before you book. Trane says to ask to see the company’s maintenance checklist first, because some companies charge extra for certain tasks. I ask for it by email. Then I have it in writing, and I can hold the invoice up against it later.

What a furnace tune-up should include

This list comes from the ENERGY STAR checklist and the gas furnace checklist inside the ACCA standard.

• The burn. The ACCA checklist has the tech run a combustion analysis and write down the result.
• Gas pressure. Measured at the inlet and at the manifold, and compared to what the maker’s data says it should be.
• The heat exchanger. Checked for rust, cracks, holes, and bulges, and for a flame that moves when the blower kicks on.
• The venting. The flue, the vent pipe, and the chimney checked for blockages, rust, cracks, and signs of water.
• The electrical side. Connections tightened, line voltage and amp draw measured, capacitors checked with a meter, relays looked at for pitting.
• Airflow. Airflow across the heat exchanger checked, and the temperature difference across it measured.
• The blower. Wheel and motor inspected and cleaned, and the amp draw written down.
• The condensate drain. Checked, because a plugged one puts water where you do not want it.
• Controls and thermostat. Including one full start and stop, to prove the system fires, runs, and shuts off the way it should.
• The filter. Changed if it needs changing. How often to change your furnace filter is the schedule for the rest of the year.

Notice how many of those end in measured or written down. That is the real test of a tune-up. It should leave numbers behind. The ACCA standard says the write-up has to name the equipment, with its make, model, serial number, year, and start-up date when that is known, plus the tasks that were done, any code violations, and any parts the tech could not get to.

A sticker on the furnace and a thumbs up is not that.

What an AC tune-up adds

Same kind of visit, cooling side. ENERGY STAR adds three jobs:

• Clean the evaporator coil and the condenser coil.
• Check the refrigerant charge and adjust it if it is off.
• Clean and adjust the blower parts. ENERGY STAR says airflow problems can cut a system’s efficiency by as much as 15 percent.

Two things are worth knowing before that visit. Trane says cleaning the coils will most likely cost extra. And the ACCA standard says these checks only count when the equipment is running inside the temperature range the maker allows. A cooling tune-up on a 50 degree day cannot honestly tell you much.

Refrigerant is where that matters most. A Department of Energy guide on air conditioner diagnostics warns that a low charge reading can be wrong: a restriction in the line, cool outdoor air, or an inaccurate gauge can all make a properly charged system look low. That same guide names slow leaks as one of the reasons systems really do end up low. So if someone adds refrigerant every year, the question is where it is going, not how much to add this time.

How to tell a needed repair from an upsell

Four questions. I ask them standing there, before I agree to anything.

1. What did you measure? A real finding comes with a number, and with the number it was supposed to be. “Your capacitor is weak” is an opinion. “Your capacitor reads 28 and the label on it says 35” is a finding. The ACCA checklist tells the tech to check capacitance with a meter, so that number exists.
2. Is this a safety problem, a this-season problem, or a someday problem? Make them sort the list. Most lists are mostly someday.
3. Can I have it in writing, with the price? The standard already asks for the finding, the recommendation, and the price. A company that will not put it in an email has told you something.
4. Can it wait until I get a second quote? A tune-up is a planned visit, not an emergency. Nothing found on a planned visit has to be bought the same hour. How to tell if a contractor quote is fair is what I do with the numbers once I have more than one.

There is one add-on worth naming. The EPA says duct cleaning has never been shown to prevent health problems, and does not recommend it on a routine schedule, only when it is actually needed. The EPA says plainly not to hire duct cleaners who sell it as a routine part of heating and cooling maintenance. If it comes up, ask to see what is in your ducts first.

ACCA also publishes a homeowner checklist of questions to ask before you sign a maintenance agreement. It is worth reading once, on a day when no tech is in your kitchen.

When the tech says your system is unsafe

This one is not a negotiation.

The ACCA standard says that if the tech finds a condition that could make the system unsafe, they have to shut the equipment off and tell you about it in writing. A shut-off is not an upsell. It is the rule they are following.

What is fair to question is what comes next. A shut-off and a same-night contract for a new furnace are two different things. Get the written notice. Leave the system off. Then call another licensed company and ask them to test it themselves, with the system still off. When to replace a furnace instead of repairing it is how I think it through once I have two opinions.

Carbon monoxide is why this is strict. The CPSC says carbon monoxide has no color and no smell, so you cannot check it yourself. The CPSC says to have the heating system professionally inspected and serviced every year, and that the inspector should also check the chimney and the flue for blockages, rust, and loose or disconnected joints. If a carbon monoxide alarm sounds, move outside to fresh air right away, call 911 from there, and do not go back in until responders say you can. If an appliance turns out to be the cause, do not run it again until someone trained has serviced it.

Write down what each visit actually did

Every question above gets easier when you can look up your own house.

“You need a new capacitor” reads differently when you know one went in 14 months ago. “This filter is filthy” reads differently when you changed it in August. “Nobody has ever cleaned this blower” reads differently when your last two visits say otherwise.

Without a record, you are standing in the basement taking a stranger’s word about a machine you cannot read. That is the exact spot a bad upsell needs you to be in.

So after every visit I write down:

• The date, the company, and the name of the tech who came
• What they measured, and the numbers
• What they recommended, and whether I said yes or no
• What they told me to watch for next time

Tobi’s maintenance log is where I keep it. The furnace is its own record in the home, with its notes and a link to its manual. The yearly tune-up is a task on that furnace that repeats, so the fall visit shows up as due instead of waiting on somebody’s memory. Marking it done adds a line to the history: the date, who did the work, and notes for that one visit. Nothing gets written over, so three years of service reads as three visits.

The company goes in as a contractor, with its trade, phone, and email. When the work is logged to them, I can open that contractor later and see everything they have done in this house. If I stop calling them, their past visits keep their name on them.

Everyone in the household sees the same record in real time, on their own iPhone or iPad, or on an Apple Silicon Mac. So whoever was home for the appointment is not the only person who knows what was said. One subscription covers the house and only the owner pays, so the people you live with cost nothing to add. The pricing page has the numbers.

Tobi does not price the job and it does not book anyone. It is the record of what happened in your own house. How to keep track of home contractors is the longer list of what to save.

What I do when the tech hands me a list

I ask for the checklist before the visit, so I know what I bought.

I ask what they measured, and I write the numbers down.

I sort the list into safety, this season, and someday, and I only buy the first one today.

Then I save the visit, so the next person who comes to look at my furnace is talking to a homeowner who already knows its history.