What happens during an HVAC tune-up or new system installation?

Updated November 10, 2026 · KeystoneProGuide editorial team

What happens on an HVAC service call?

A technician diagnoses the problem, tells you what failed and what it will cost, and fixes it once you agree. HomeAdvisor, a cost survey, says most companies charge an initial service call of $100 to $250 on top of labor, and that rates rise for after-hours emergencies. Its furnace page adds a trip fee equal to at least one hour of labor, with extra charges on weekends, holidays and at night.

Before the visit, have ready what ENERGY STAR suggests telling any contractor: the model of your system, its maintenance history, and which rooms are uncomfortable. When the diagnosis comes, ask for it in writing with the part and the price. If the technician recommends replacement instead of repair, ask what the repair would cost so you can compare.

What should a seasonal tune-up include?

ENERGY STAR's maintenance checklist is the best yardstick. It lists what a typical check-up should include:

1. Check the thermostat settings.
2. Tighten electrical connections and measure voltage and current on the motors.
3. Lubricate moving parts.
4. Check and clear the condensate drain.
5. For heating: check the gas or oil connections, gas pressure, burner combustion and heat exchanger.
6. For cooling: clean the evaporator and condenser coils, check the refrigerant level and adjust it if necessary, and clean and adjust the blower.
7. Check the controls and the starting cycle, so the system starts, runs and shuts off properly.
8. Inspect, clean or change the filter, and show you how to do it yourself.

The Consumer Product Safety Commission adds that the heating inspection should check chimneys and flues for blockages, corrosion and disconnections. Ask for a written list of what was checked and what was found. HomeAdvisor gives $80 to $100 for an inspection and $125 to $200 for a full tune-up, nationally.

What happens before a new system is installed?

An estimate visit, then paperwork.

• The home evaluation. ENERGY STAR says a contractor should spend significant time inspecting your current system and your home, size the new equipment to the house rather than a rule of thumb, and inspect the ducts.
• The written proposal. It should give project costs, model numbers, the job schedule and warranty terms, and you should sign it before work starts.
• The permit. In Pennsylvania, installing or replacing a gas or mechanical system in a home generally needs a permit from the municipal building code official. An emergency replacement may be done first if the application follows within 3 business days. In Philadelphia, the contractor must be identified and confirm it is on the job before the city issues a permit.
• The deposit. The Federal Trade Commission advises not paying the full amount up front.

What happens on installation day?

Removal, installation, then testing. How long it takes depends on the job. HomeAdvisor says a central air conditioner installation usually takes four to eight hours. Removing the old furnace is a separate line on some quotes; Angi lists it at $60 to $330.

ENERGY STAR's description of a quality installation tells you what the crew should do before they leave:

• Set the airflow to meet the manufacturer's specifications. Poor airflow can mean lower efficiency, higher bills and overly damp air.
• Test and adjust the refrigerant charge of an air conditioner or heat pump.
• Inspect the ducts, perform a leakage test and make necessary repairs.
• Confirm the size was chosen from the house's actual characteristics.

For a gas or oil furnace or boiler, ask the installer to show you how the new unit is vented and that the connection to the flue or vent pipe is secure.

What happens after the work is done?

Inspection. Where a permit was issued, the municipality inspects the work. In Philadelphia, the city issues a Certificate of Approval once all required inspections are passed, and its forms for one- and two-family homes include an HVAC Equipment Certificate and a Duct and Envelope Testing Certificate for the inspector.

Warranty registration. The FTC says some warranties require you to return a registration card to qualify for service, and that you should keep the warranty with your receipt, which proves the purchase date. Do it the week the system goes in.

Final payment. The FTC advises not making the final payment until the work is done and you are satisfied.

A walk-through. Before the crew leaves, ask to be shown the filter location and size, the thermostat settings and any maintenance the manufacturer requires to keep the warranty valid.

How do you know the job was done properly?

Compare what happened with the proposal: the model numbers on the units, the items the quality-installation list expects, and the permit and inspection. If something is missing, raise it in writing while the crew can still come back. Questions worth putting to the contractor in advance are in questions to ask an HVAC contractor, and price ranges are in the cost guide. Contractors are listed on the HVAC contractors directory page.

Sources

1. How Much Does HVAC Repair Cost?, HomeAdvisor
2. How Much Does It Cost to Repair a Furnace?, HomeAdvisor
3. How Much Does an AC Unit Cost?, HomeAdvisor
4. Maintenance Checklist, ENERGY STAR
5. HVAC Quality Installation, ENERGY STAR
6. 10 Tips for Hiring a Heating and Cooling Contractor, ENERGY STAR
7. 34 Pa. Code § 403.62. Permit requirements and exemptions., Commonwealth of Pennsylvania (Pennsylvania Code)
8. Get a Mechanical Permit, City of Philadelphia
9. How Much Does a New Furnace Cost? [2026 Data], Angi
10. Warranties, Federal Trade Commission
11. How To Avoid a Home Improvement Scam, Federal Trade Commission
12. Carbon Monoxide Fact Sheet, U.S. Consumer Product Safety Commission