HVAC FAQs: Straight Answers From a San Antonio HVAC Team

It depends on the system type, size, efficiency rating, ductwork and installation details, so there is no honest one-size price. Send us a photo of your equipment’s nameplate and we can send a same-day price estimate. Your final price is confirmed in writing after an in-home or photo-based assessment. See HVAC system replacement for what goes into the price.

Yes. Text or email a clear photo of the nameplate (the metal label) on your outdoor unit and your indoor unit. The nameplate shows the model, size and age of your equipment, so we can price a comparable system and send a same-day estimate, then confirm it after a short assessment.

Estimates for new system installations and replacements are free. For repairs, a technician diagnoses the problem first and gives you a written price before any repair starts, so you always know the cost before you say yes.

Quotes often compare different things: equipment size and efficiency, whether the indoor coil is replaced to match the outdoor unit, and what is included, such as the line set, drain, pad, electrical, thermostat, permit and haul-away. Ask every company for a written, itemized quote so you can compare like for like. Our HVAC second opinion page shows what a complete quote should list.

Yes. Financing is available for qualified homeowners, so a new system does not have to wait for the perfect month. We explain the options in plain language and help you apply.

We run offers from time to time. Ask about current offers when you call, and we will tell you what applies to your project. Terms apply.

CPS Energy offers rebates to its customers for qualifying central air conditioners and heat pumps, based on the size and efficiency of the equipment, and the customer applies through CPS Energy. The federal 25C tax credit for home HVAC equipment ended for systems installed after December 31, 2025. Rebate rules change, so check the current CPS Energy program before you buy.

Use the $5,000 rule as a starting point: multiply the age of your system by the repair cost. If the total is more than $5,000, replacement is usually the better investment. It is a rule of thumb, not a verdict, so we also look at refrigerant type, repair history and how well the system cools your home before we recommend anything.

Most air conditioners in South Texas last about 12 to 15 years, because they run hard through long, hot cooling seasons. Gas furnaces often last longer. Regular maintenance helps a system reach the long end of that range. Age alone is not the deciding factor; condition and repair history matter too.

R-22 has not been produced or imported in the U.S. since 2020, so recharging an R-22 system is expensive and supplies keep shrinking. Small repairs can still make sense, but if an R-22 system needs refrigerant or a major part, replacement is usually the better choice.

New systems now use lower-impact refrigerants such as R-454B and R-32, after an EPA rule that took effect in 2025. Existing R-410A systems are still legal to use and can still be repaired and recharged. R-410A will become less available and more expensive over time, which is worth weighing if your system is older and needs a major repair.

The right size comes from a load calculation of your home, not from the size of your old unit or the square footage alone. We look at insulation, windows, sun exposure, layout and ductwork. An oversized system cools quickly but leaves the house clammy, and an undersized one runs nonstop and still cannot keep up.

New central air conditioners in Texas must meet at least 14.3 SEER2 for split systems. Higher SEER2 systems cost more up front but use less electricity, which matters in a city where the AC runs for most of the year. Two-stage and variable-speed systems also remove more humidity. We show you the options side by side so you can choose what fits your budget.

Common causes are a clogged air filter, the thermostat fan set to On instead of Auto, a dirty outdoor coil, a failed capacitor or contactor, low refrigerant from a leak, or a frozen indoor coil. Check the filter and thermostat first. If that does not fix it, call for AC repair.

Make sure the thermostat is set to Cool and below the room temperature, check the breakers for the outdoor unit and the indoor unit, replace a dirty filter, and confirm the outdoor unit and its fan are running. If you see ice on the refrigerant lines, turn the system off and let it thaw before you call.

Ice usually means restricted airflow, often from a dirty filter, blocked vents or a dirty indoor coil, or low refrigerant from a leak. Turn the system off and let it thaw, because running it with ice can damage the compressor. Then call us so we can find the cause.

Most indoor leaks come from a clogged condensate drain line or an overflowing drain pan. In South Texas the AC pulls a lot of moisture out of the air, so drains clog more often. A tune-up includes clearing and flushing the drain line and checking the safety switch.

On the hottest San Antonio and Austin afternoons, a correctly sized system may run almost continuously and still hold the temperature, which is normal. It is not normal if the house keeps getting warmer, the air from the vents is not cold or the system never shuts off in the evening. Those signs point to a problem worth checking.

Heat rises, and many two-story homes have long duct runs through hot attics, so upstairs rooms get less cool air. Leaky or undersized ducts and a system that is the wrong size make it worse. We check airflow, duct connections and system size before recommending a fix, from ductwork repair to a separate upstairs system.

High summer bills usually come from an aging or poorly maintained system, a dirty filter or coil, leaky ductwork in a hot attic or a system that is the wrong size. A tune-up and a duct inspection are good first steps. If your system is older and inefficient, replacement may be worth comparing.

ENERGY STAR recommends 78°F when you are home and awake, and setting it higher when you are asleep or away. Every degree higher reduces how hard your AC works. A smart thermostat can handle those changes for you on a schedule.

The usual causes are a dirty flame sensor, a failed igniter, a clogged filter that trips the high-limit switch or the thermostat fan set to On. Check the filter and thermostat first. If the heat still will not come on, call for heating repair.

For many homes, yes. A heat pump cools in summer and heats in winter with one outdoor unit, and South Texas winters are mild. Compared with electric strip heat, a heat pump uses far less electricity for the same warmth. Compared with gas heat, the answer depends on your electric and gas rates, so we compare both for your home.

A dusty smell the first time you turn on the heat each season is normal and usually fades within an hour. A strong electrical, burning plastic or gas smell is not normal. Turn the system off and call for service. If you smell gas, leave the home and call your gas utility.

If you have a gas furnace, water heater or other gas appliance, yes. The CDC recommends a battery-operated or battery back-up carbon monoxide detector in your home. A fall heating tune-up also includes checking venting and carbon monoxide levels at the equipment.

Twice a year: your cooling system in the spring and your heating system in the fall. Regular maintenance helps prevent summer breakdowns, keeps the system running efficiently and catches small problems before they become expensive repairs.

Check it every month and change it at least every three months. In San Antonio summers, homes with pets or allergies and dusty homes often need a new filter every month. A clogged filter is one of the most common causes of poor cooling and frozen coils.

A spring cooling visit includes checking refrigerant pressures and temperature split, testing electrical parts and motors, rinsing the outdoor coil, flushing the condensate drain and checking the thermostat and airflow. A fall heating visit covers burners, ignition, the heat exchanger where visible, safety controls, gas pressure, venting and carbon monoxide levels.

Yes. With our Comfort Club maintenance plan, we schedule your spring cooling tune-up and fall heating tune-up for you, follow a written checklist on every visit and send a summary of what we checked and what to plan for.

Only when there is a reason. The EPA advises cleaning ducts as needed, not as routine maintenance. Cleaning makes sense if you see substantial mold, signs of pests, heavy dust blowing from the vents or debris left after a remodel. If none of those apply, we will tell you. See air duct cleaning.

Most straightforward change-outs are finished in one day. Jobs that include ductwork changes, a packaged unit on a roof or a switch from a furnace to a heat pump can take longer, and we tell you the schedule up front.

Yes. Replacing heating and cooling equipment inside San Antonio city limits requires a city mechanical permit, and other cities have their own rules. We pull the required permit as part of the installation, and the permit number can also be needed for some utility rebates.

Modern Air Systems provides a 1-year labor warranty on system replacements. New equipment also carries the manufacturer’s parts warranty, typically 10 years when the equipment is registered, subject to the manufacturer’s terms. We help you register your equipment so that coverage is in place.

We schedule repairs as quickly as we can during business hours, and calling early in the day gives you the best chance at the soonest appointment. When you call, tell us what the system is doing so we can send the right technician with the right parts.

We are open Monday through Friday from 8 AM to 6 PM and Saturday from 8 AM to 6 PM. Call (210) 222-0201 in the San Antonio area or (737) 222-0414 in the Austin area.

We serve San Antonio, North San Antonio, New Braunfels, San Marcos, Austin and Round Rock, plus nearby communities such as Stone Oak, Boerne, Schertz, Kyle, Buda, Cedar Park, Pflugerville and Georgetown. See all of our service areas.

Yes. Modern Air Systems is licensed and insured in Texas under Texas ACR contractor license TACLB27872E, and our technicians are background-checked. You can verify any HVAC contractor’s license through the Texas Department of Licensing and Regulation license search.

Yes. If another company told you that you need a new system or an expensive repair, we will test the system and give you an honest second opinion. Many expensive quotes start with a real symptom and the wrong cause, such as a failed capacitor called a bad compressor.

Yes. We work with landlords and property managers on tenant repairs and maintenance, and with small businesses on light commercial HVAC, including rooftop and packaged units.

Yes. Ductless mini splits work well for additions, garages, converted spaces and rooms that never stay comfortable. See ductless mini split installation for how they compare with central air.