How to Choose an HVAC Contractor: 11 Questions, $75 to $250

HVAC license rules from state and city agencies, as published on our HVAC city pages (checked October 2026), plus the federal refrigerant rule.

When is a heating or AC problem urgent?

A carbon monoxide alarm or a gas smell comes before any hiring decision: leave the house, then call 911 or the gas utility from outside. CPSC says to have the heating system professionally inspected every year, which is the cheaper way to stay out of that situation.

• Now: a CO alarm, a gas smell, no heat with pipes at risk of freezing, or no cooling for someone vulnerable in a heat wave. See emergency HVAC repair.
• This week: a system that runs but does not keep up, short cycles or makes a new noise.
• Can wait: a replacement of a working but aging system. This is where ENERGY STAR's advice on written, itemized bids pays off.

Emergency labor costs more: HomeGuide puts it at $140 to $250 an hour, and some companies add $40 to $80 an hour for nights and weekends. The FTC's Cooling-Off Rule does not cover emergency repairs or service you asked for, so agree on the price before work starts.

How do I check an HVAC contractor's license?

Get the license number and class, then search it on the state or city agency's lookup; HVAC licensing differs more by state than most trades, as the table above shows.

Texas licenses air conditioning and refrigeration contractors through TDLR, in Class A or Class B. Florida uses the same A and B split under its statutes, plus a mechanical contractor license. California uses CSLB's C-20, Arizona's ROC uses R-39R, and Nevada uses C-21. Georgia licenses conditioned air contractors through the Secretary of State, and North Carolina licenses heating contractors as H1, H2 or H3.

Colorado has no state HVAC license, so Denver licenses contractors itself, and it does not accept licenses from other counties or states. In Missouri, Kansas City licenses HVAC trades itself. Whatever the license, refrigerant work also needs a technician with EPA Section 608 certification. City pages show the local lookup: HVAC repair in Houston, HVAC repair in Denver and HVAC repair in Los Angeles.

What questions should I ask an HVAC contractor before hiring?

Ask about the license class, refrigerant certification, how the system will be sized and what the written proposal includes. For a repair, skip the sizing and duct questions; for a new system, ask all eleven:

1. What is your state or city license number and class? In Texas and Florida, a Class B license is limited to cooling systems of 25 tons, while Class A has no size limit.
2. Are your technicians EPA Section 608 certified? EPA requires it for anyone who maintains, services or repairs equipment that could release refrigerant.
3. Are any of your technicians NATE certified? NATE (North American Technician Excellence) is voluntary and most certifications must be renewed every two years; Carrier says to ask for the NATE ID and check it on NATE's verification tool.
4. Will you do a load calculation before quoting a new system? ENERGY STAR says "a bigger system isn't always better" and that a good contractor sizes equipment to the house.
5. Will you check the ducts? ENERGY STAR expects a contractor to check ducts for leaks, insulation and airflow as part of a home evaluation.
6. Can I get a written, itemized proposal with model numbers? ENERGY STAR says to sign a written proposal covering costs, model numbers, the job schedule and warranty before work starts.
7. Who pulls the permit? North Carolina law takes HVAC replacements out of its small-job permit exemption, so a new furnace, heat pump or AC there needs one.
8. Is the service call fee credited to the repair? HomeGuide puts the fee at $75 to $200 and says it is often applied to the first hour.
9. If refrigerant is low, where is the leak? HomeGuide says an AC never needs more refrigerant unless there is a leak, so a yearly top-off without a repair is a warning.
10. Do you qualify for the utility rebate? Some rebates require a licensed contractor; in Georgia, Atlanta Gas Light's furnace rebate needs a Georgia-licensed HVAC contractor.
11. What does a maintenance plan cost, and what does it include? HomeGuide puts plans at $150 to $300 a year and a tune-up at $70 to $200; CPSC says to have the heating system inspected every year.

NATE certification is a training credential, not a license. Carrier, which ties its dealer program to it, says that "certification alone does not guarantee the quality of a particular installation, repair or service visit." Treat it as one point in a company's favor, after the license.

What are the red flags with HVAC contractors?

The HVAC-specific red flags are repeated refrigerant top-offs, system sizing without a home visit and tax credits that no longer exist. These come from HomeGuide, ENERGY STAR, the IRS, the FTC and Denver's licensing office:

• Refrigerant top-offs every season with no leak repair. HomeGuide says an AC never needs more refrigerant unless there is a leak.
• A new system quoted by square footage alone, with no visit. ENERGY STAR says a bigger system is not always better and expects a home evaluation.
• A federal tax credit promised on a 2026 installation. The IRS says the 25C credit "will not be allowed for any property placed in service after December 31, 2025."
• No written proposal with model numbers. ENERGY STAR says to sign one before work starts.
• An out-of-state license in a city that licenses locally. Denver says it does not accept or reciprocate contractor licenses from other counties or states.
• Pressure to replace today, a door-to-door pitch, or cash only. All three are FTC scam signs.
• They want you to get the permit. Also on the FTC's list.
• No one can say who handles the refrigerant. EPA requires Section 608 certification for that work.

How much should an HVAC company charge for the first visit?

An HVAC service call costs $75 to $200 in HomeGuide's figures and $100 to $250 in HomeAdvisor's 2026 guide, often applied to the first hour. HomeAdvisor's average repair is $350, with most between $130 and $2,000, and HomeGuide puts most repairs at $150 to $450. Prices by part and by symptom are on HVAC repair costs, AC repair and furnace repair.

What should be in an HVAC contract or proposal?

A written proposal should list costs, model numbers, the job schedule and warranty, ENERGY STAR says, and the FTC adds the contractor's name, address, phone and license number. For HVAC work, also look for:

• Equipment by model number for the outdoor unit, the indoor coil or furnace and the thermostat, so you can compare bids line by line.
• The sizing basis: what load or evaluation the size came from.
• Duct work, if any, priced separately.
• The permit and who pulls it.
• Deposit terms. In California, CSLB caps the down payment at $1,000 or 10 percent of the contract, whichever is less.
• Rebate paperwork: who files it and by when.

Where do I complain about an HVAC contractor?

File with the agency that issued the license, then with your state attorney general or a local consumer protection office, the routes the FTC lists. Send follow-ups in writing and keep copies.

• California: CSLB takes complaints for up to four years.
• Arizona: the ROC, within two years of the last work on a repair; its Recovery Fund can pay up to $30,000 per claimant on an owner-occupied home.
• Nevada: the NSCB Residential Recovery Fund pays up to $40,000 per claim on owner-occupied single-family homes.
• Florida: DBPR's complaint form.
• Texas: the Attorney General's consumer complaint form.
• Denver: the Denver District Attorney's consumer protection office.

How our heating and AC line fits in

Our heating and AC line connects you to an independent local company that pays us for the referral. We do not license, vet or rate them, so ask whoever answers for the license number and class and the service call fee, and look the license up yourself. How calls work explains the referral.

What to do before you call an HVAC company

1. If a CO alarm sounds or you smell gas, leave first and call from outside.
2. Check the thermostat setting, the breaker and the filter.
3. Write down the brand, model and age of the system from its label.
4. Note what it is doing: no start, blowing warm or cold air, noise, ice, water.
5. On the call, ask for the license number and class and the service call fee.
6. For a replacement, get at least two written, itemized proposals before you sign.