Commercial HVAC Service: How to Hire a Contractor

Commercial AC repair: describe the job before dispatch

Give the contractor the building address, equipment make and model if known, affected areas, operating hours, and any error messages. Explain whether the system is not running, not cooling, leaking water, or serving some spaces poorly. If you rent the space, confirm with the owner who can authorize work and payment.

• Do you service this equipment type and its controls?
• What does the diagnostic visit include, and what is charged separately?
• Will you provide a written diagnosis and estimate before repairs?
• What happens if a part is unavailable or another visit is needed?

For fee questions, use our HVAC repair and service-call cost guide. Get a quote for your equipment and scope rather than applying a home repair estimate to a commercial job.

Rooftop units: ask about access and controls

For a rooftop unit, ask who will arrange roof access and coordinate with the building owner. Have the contractor explain how the visit will address the cooling or heating fault, airflow, controls, and outside-air settings where applicable. Do not climb onto the roof to diagnose the equipment yourself.

The Department of Energy's HVAC commissioning guidance describes checking operation against the design and engineering documentation. It also recommends checking outside-air dampers and controls on systems with economizers or demand-controlled ventilation, along with operating schedules and setpoints. Ask what testing and written results your contractor will provide.

What to put in a commercial HVAC maintenance agreement

Compare the actual agreement rather than the phrase “preventive maintenance.” Ask for an equipment list and a task schedule based on the equipment instructions and how the building is used.

• Covered equipment: Identify each rooftop unit, air handler, thermostat, and control system in scope.
• Visit tasks: Ask which inspections, filter changes, coil cleaning, drain checks, and control checks are included or excluded.
• Documentation: Request a service report with findings, completed work, and recommended follow-up for each unit.
• Repair authorization: Name the person who can approve extra work and require an estimate before it begins.
• Emergency terms: Ask whether priority service means a guaranteed response time, an earlier place in the queue, or something else. Put the terms in writing.
• Billing and renewal: Confirm parts and labor exclusions, after-hours charges, cancellation terms, and any automatic renewal.

Check licensing for the project and scope

Ask which contractor license or registration applies to the proposed work at the building address. Request the business's legal name and applicable credential details, then check with the responsible authority. Ask specifically whether the credential covers the commercial work being proposed. A directory entry is not proof of an active license.

For your state, start with the state licensing directory and confirm the proposed scope with the official authority before hiring.

Commercial HVAC in Boston and Nashville: permit questions

For a repair, equipment replacement, or installation, ask the local permit office which approvals and inspections apply to that specific scope and address. Have the proposal identify who handles any required application and inspection. Do not assume a maintenance visit and a rooftop-unit replacement have the same permit requirements.

• Boston: Contact Boston Inspectional Services about the project scope. The city's new-construction permit guidance lists HVAC and energy plans for building review; it is not a blanket rule for routine repairs.
• Nashville: Review Metro Nashville's Gas/Mechanical Trade Permit information and ask Codes which permits and inspections apply to the work.

Commercial emergency service and after-hours calls

Before authorizing dispatch, confirm that a technician can attend your building, the arrival estimate, site access, and the after-hours billing terms. Ask whether the visit is for diagnosis, a temporary measure, or a completed repair, and what happens if parts are unavailable. Do not read “24-hour” as a promised arrival time.

If there is a gas smell or a CO alarm, leave the building and call emergency services from outside. Follow the official safety sources in our emergency HVAC guide before arranging contractor service.