Ductwork Repair, Sealing & Replacement
Better airflow, even temperatures, and lower bills, proper ductwork from the family-run Morgan Hill team that’s served the South Bay since 2009.
Licensed & insured, CA CSLB #935704 · All brands · Financing available
We answer 24/7 (408) 497-0444
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The Hidden Half of Your HVAC System
You can install the best furnace or heat pump on the market, but if the ductwork delivering that air is leaky, undersized, or poorly designed, your home will never feel right. Ducts are the part of the system most homeowners never see, and the part that quietly causes uneven temperatures, weak airflow, dusty rooms, and higher bills. Modern Air has been getting ductwork right across the South Bay since 2009.

What We Do
- Duct sealing, We find and seal leaks at joints, connections, and registers so the air you pay to heat and cool actually reaches your living space instead of the attic or crawlspace.
- Duct repair, Fixing crushed, disconnected, or deteriorated sections and poorly supported runs that restrict airflow.
- Duct replacement & redesign, When ducts are badly aged or were never sized correctly, we replace and redesign them to match your equipment and your home’s airflow needs.
- Airflow balancing, Adjusting the system so every room gets its fair share, fixing the “freezing in one room, stuffy in another” problem.

Why Right-Sizing Matters
One of the most common problems we find is ductwork that simply can’t handle the equipment connected to it. A system that’s too large for its ducts strains itself, runs inefficiently, and wears out early. We’ve had to be honest with homeowners about this, sometimes the right answer is properly sized ducts and equipment that matches them, not the biggest unit money can buy. Doing it right beats doing it big every time.
Duct sizing is where good installs live or die, and we take it seriously enough to walk away from a paid job. A long-time customer once wanted his new heat pump connected to ductwork we’d already flagged as undersized, and rather than do the job wrong, Andrew removed the equipment and refunded him in full. We won’t hook new equipment up to ducts that will choke it.
Comfort and Efficiency You’ll Notice
Sealed, well-designed ductwork pays you back in even temperatures, quieter operation, cleaner air, and lower energy bills. Modern Air also handles indoor air quality, cooling, and heating, so we look at the whole system and fix the actual cause of your comfort problems. An experienced technician will inspect your ducts, explain what’s happening in plain language, and quote the work upfront, and our HVAC cost breakdown shows the ranges before you call. Call or text (408) 497-0444 to get started.
A Simple, Transparent Process
Call or text us
(408) 497-0444, or send the form and we reach out the same day.
Same-day diagnosis
A local, background-checked tech finds the problem and quotes it upfront.
Fixed right, guaranteed
Clear pricing before work starts. Financing if you need it.
All Major HVAC Brands
What South Bay Customers Say
“Stephen has been great every time he’s come to work on the hvac! We really appreciate your amazing customer service!”
Suzanna S.Santa Cruz · HVAC service“Superb! True class act. Astounding service and professionalism. Will absolutely hire them again in the future.”
Kory G.San Jose · HVAC service“These guys are great. Arrive on time, knowledgeable and thorough. We signed up for their maintenance plan and are very happy with it.”
Amy S.Palo Alto · HVAC maintenanceFrequently Asked Questions
How do I know if my ductwork is the problem?
Tell-tale signs include rooms that never get comfortable, weak airflow from some vents, rising energy bills, and excess dust. Leaky or undersized ducts force your system to work harder for worse results. Modern Air inspects the whole duct system and pinpoints where the air is being lost.
Can undersized ducts really hurt my new system?
Absolutely. We’ve seen homes where the ductwork was too small for the equipment installed on it, which strains the system and shortens its life. When ducts can’t handle the airflow, even brand-new equipment underperforms. Right-sizing the ducts to the system is part of doing the job correctly.
What’s involved in duct sealing?
We locate leaks at joints, connections, and registers and seal them properly so conditioned air reaches your rooms instead of your attic or crawlspace. It’s one of the most cost-effective ways to improve comfort and efficiency.
Do you repair ducts or only replace them?
Both. Often targeted repair and sealing solve the problem affordably. When ducts are badly deteriorated, undersized, or poorly designed, replacement is the better long-term fix, and Modern Air will tell you honestly which one your home needs.
Schedule Your Free Estimate Today
Call, text, or send the form, a local technician gets back to you the same day.
Call or Text (408) 497-0444