New home HVAC warranty: what the builder covers, what the manufacturer covers, and the 11-month check

Updated November 1, 2026 · Claude AC · Editorial lead: Jean-Claude Fatemian · 7 sources cited

A new home HVAC warranty is really two warranties with different owners. The builder answers for how the system was designed and installed in your house, usually for one or two years from closing. The manufacturer answers for defective parts in the equipment, often for five years, or ten if the equipment is registered in time. Most disputes come from mixing them up, and from one date: the eleventh month, the last moment to put everything in writing before the builder's first year ends.

Two warranties, two different questions

The builder's warranty answers the question "was the system put in properly?" A bedroom that never gets near the thermostat setting, a missing return, a crushed duct in the attic, a drain that overflows, a refrigerant line that leaks at a joint: those are installation and design problems, and in the first year or two they are the builder's to fix, even though an HVAC subcontractor did the work. You normally deal with the builder's warranty department, not with the subcontractor directly.

The manufacturer's warranty answers "did a part fail because it was defective?" A compressor, a control board or a coil that fails from a manufacturing defect is the manufacturer's, but on most residential equipment that covers the part only, not the labor to diagnose and replace it, and not the refrigerant. In the first year or two of a new house, ask the builder who provides that labor before calling anyone yourself.

What the builder covers, and for how long

Many builders use a "1-2-10" structure: one year for workmanship and materials, two years for plumbing, electrical, heating and cooling systems, ten years for major structural defects. It is common, not a federal rule, and your own document may cover the HVAC system for one year only. Some states write the terms into law, and the details differ:

• Minnesota gives a two-year warranty against defects caused by faulty installation of plumbing, electrical, heating and cooling systems due to noncompliance with building standards (Minnesota Statutes, section 327A.02), but excludes damage not reported to the builder in writing within six months after you discover it or should have (section 327A.03).
• Virginia gives implied warranties on a new dwelling for one year from the transfer of title or possession, whichever comes first, with notice by certified mail or commercial overnight delivery (Code of Virginia, section 55.1-357).
• New Jersey runs a state New Home Warranty program: two years for mechanical systems, with written performance standards and strict filing deadlines, covered below.
• If your loan is FHA-insured, HUD requires a one-year Warranty of Completion of Construction (form HUD-92544), which starts at the transfer of title, completion or occupancy, whichever comes first.

What "covered" means in practice is often left vague. New Jersey's homeowner booklet is a useful benchmark because it is precise: where air conditioning is provided, the system must be capable of maintaining 78 °F in the center of each room, five feet above the floor, under the local summer design conditions, and the heating 70 °F under winter design conditions. It also treats leaking refrigerant lines in the first two years, ductwork that comes apart and ducts left uninsulated in attics, garages and crawlspaces as deficiencies, while the continued maintenance of the condensate drain is the owner's job. If your builder's warranty contains no standard of its own, those figures are a reasonable way to frame a complaint about a room that will not cool.

When the manufacturer's clock starts on a new house

On a new build the outdoor unit may be installed months before you close, and brands handle that gap differently. Lennox's registration page says eligible equipment must be registered within 60 calendar days of installation for existing homes, or of the closing date for new construction. Trane's page says its registered limited warranty is available only to products registered within 60 days of installation, without mentioning closing. Our guide to HVAC warranty registration covers the parts and labor split and the state exceptions; on a new house, three habits avoid most losses:

• Photograph every nameplate before or at closing (outdoor unit, indoor coil, air handler or furnace); our guide to reading an AC nameplate shows where each number is.
• Ask the builder in writing whether the equipment was already registered, by whom, in whose name and from what date.
• Register each unit yourself in the first week after closing, on the manufacturer's own site, and keep the confirmation.

Keep the paperwork that proves the work was inspected as well: the permit and final inspection record, explained in our guide to HVAC permits and inspection, and the AHRI certificate of the matched system.

Why the first year deserves real attention

New systems fail less often than they underperform, and underperformance is exactly what a builder warranty covers. A National Institute of Standards and Technology study that simulated installation faults on a heat pump in a single-family house found that duct leakage, refrigerant undercharge, an oversized unit with nominal ductwork, low indoor airflow from undersized ducts and refrigerant overcharge had the most potential to degrade performance and raise annual energy use, and that some combinations (duct leakage with undercharge) were far worse than their sum. It also noted that occupants who lower the thermostat to fight the humidity these faults cause add significantly to energy use. Every one of those faults is set at installation, and the first year is when the builder still answers for it.

If the house was ENERGY STAR certified, ask for the HVAC commissioning or grading results. The program's commissioning checklist, for instance, records the refrigerant charge against the manufacturer's goal and requires measured fan airflow within 15 % of the design airflow. Those sheets are the closest thing to a test report you will get, and they make a much stronger starting point for a claim than "upstairs feels warm".

The 11-month check

The eleventh month is the last comfortable moment to find and report everything still owed under the first-year coverage. Many builders schedule their own year-end visit; it helps, but the list should be yours.

1. Book in month 10 for a date in month 11, with an independent home inspector, an HVAC contractor who is not the builder's subcontractor, or both. Ask for a dated written report with measurements and photos.
2. Bring your evidence: a temperature log for the problem rooms on hot and cold days, measured in the center of the room about five feet up, with the thermostat setting and the outdoor temperature.
3. Check the system: airflow at every register with bedroom doors closed, return paths, the temperature difference between return and supply air (commonly around 16 to 22 °F on a healthy system in cooling, as an indicator only), the primary and secondary drains and the overflow switch, the attic ducts and the line set insulation.
4. Send one numbered list in writing through the warranty's channel, before the anniversary, with the date each item was first reported. Use certified mail where your state or warranty requires it.
5. Ask for a written answer item by item, with a repair date, and keep anything unresolved open in your log.

Deadlines can be unforgiving. New Jersey's booklet, for example, says you must notify the builder in writing no later than seven days after the warranty for an item expires, and if the builder does not inspect and repair within 30 days of your notice, you have 14 days to file with the state program; a claim filed late is denied even if the builder promised a repair for later, such as an air conditioning fix postponed to the summer.

If you would rather work through this with checklists and ready-to-send letters, our printable new-build home HVAC checklist and 11-month warranty kit covers the documents to request before closing, a room-by-room walkthrough, registration at closing, the 11-month inspection and six letters to the builder.

Frequently asked questions

Does a new home come with an HVAC warranty?

Usually two: the builder's warranty on the design and installation, often one or two years, and the manufacturer's warranty on the equipment, often five years of parts or ten if registered in time. Some states add a statutory warranty, and FHA-insured new homes carry a one-year HUD builder warranty.

Is the HVAC covered for two years on a new house?

Often, but not always. Many builder warranties cover mechanical systems for two years, and Minnesota and New Jersey set two years for heating and cooling installation defects. Your builder's document and your state law decide; some cover only one year.

Who do I call when the AC stops working in a new house?

The builder's warranty department first, in writing, unless the warranty tells you otherwise. Even when a part is defective, the builder or its subcontractor often handles the labor in the first year or two, and calling another contractor without agreement can void that coverage. For a real emergency, make it safe, notify the builder at once and keep every invoice.

When does the manufacturer warranty start on a new build?

It depends on the brand. Lennox counts its 60-day registration window from the closing date for new construction; Trane's page counts 60 days from installation. Register in the first week after closing to stay inside the shortest window.

Is a room that is a few degrees warmer a defect?

Not necessarily. Orientation and a single thermostat for several floors create differences, and very hot days can exceed the design conditions. A room that stays well above the setting on ordinary days, with weak airflow or no return path, is worth reporting with measurements.

Read next

• HVAC warranties: the registration deadline that doubles your coverage
• Does a home warranty cover your air conditioner? Reading it before August
• Cleaning a mini-split: the blower wheel, the pan, and the smell that keeps coming back
• Homeowners insurance and your air conditioner: what a claim actually pays
• Smart thermostats: where the savings actually come from

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