SM Air / San Marcos Air Conditioning Inc.

SM Air / San Marcos Air Conditioning Inc. We serve the HVAC needs of residential and commercial customers between Austin and San Antonio.

With a team of 40 full-time employees, SM Air / San Marcos Air Conditioning serves the residential and commercial HVAC needs of customers in the Austin - San Antonio corridor.

09/10/2026

Why is your AC struggling to keep up during the hottest part of the day? When your thermostat is set to 74 degrees but the indoor temperature creeps up into the high 70s, it is a clear sign your HVAC system needs a complete diagnostic check.
When a unit fails to hold temperature in extreme heat, we perform a systematic inspection of every critical component:
Temperature split (Delta T) across the ev***rator coil
High-side and low-side refrigerant pressures, superheat, and subcooling
Air filter, ev***rator coil, and outdoor condenser cleanliness
Compressor, condenser fan motor, and indoor blower motor amp draws
Contactors and capacitors
A thorough diagnostic pinpoints whether the issue is airflow restriction, dirty coils, or failing electrical parts before it leads to a total breakdown.

09/07/2026

A common question we get asked is how all the AC ducts connect to the main HVAC system to distribute air throughout the house. The answer lies in a crucial component called the supply plenum.
We are currently up in the attic preparing a new supply plenum for installation. Here is a look at our process:
We carefully measure out the AC ducts to determine the exact length needed for each run.
We prepare the supply plenum, which acts as the central hub where all the supply ducts will eventually connect.
We completely tape and seal the edges of the plenum to secure it.
Properly sealing your duct connections is essential for a highly efficient HVAC system!

09/03/2026

A frequent question we get is how to fix poor airflow. The problem is often right in the attic!
Today, our team completed a full rip-out of all old ductwork in a customer's attic. The previous setup was inefficient, with the plenum extending far out and ducts running in multiple different directions. Those runs were unnecessarily long, which restricts proper air movement throughout the house.
Our Solution for Better Airflow:
Complete Removal: We cleared out all the old, tangled ductwork.
Direct Routing: We are installing new, completely straight runs directly to the plenum.
Fast Turnaround: We are getting everything ready before the customer returns home today.
Straight duct runs are the key to mastering your airflow!

08/31/2026

When extreme summer heat hits, your HVAC system must work overtime to keep your home cool. We get asked all the time what homeowners can do to prevent AC breakdowns during intense heatwaves.
Here are a few quick tips to protect your unit:
Change air filters regularly: Dirty filters restrict airflow and force your system to work much harder.
Clear around the outdoor unit: Keep dirt, grass, and debris at least two feet away from the condenser.
Block direct sunlight: Keep blinds and curtains closed during peak afternoon sun to reduce indoor heat gain.
Avoid drastic thermostat drops: Setting your thermostat too low in extreme heat will not cool your house faster and can freeze the coils.
If your AC is struggling to hold temperature, blowing warm air, or making strange noises, reach out to our team today!

08/27/2026

When temperatures push past 100 degrees, an AC breakdown quickly turns from an inconvenience into an emergency. We get asked all the time: what should you do if your cooling system stops working during a severe heatwave?
First, check your air filter and thermostat settings to make sure it is not a simple issue. If the system still will not run or is blowing warm air, turn it off at the thermostat to prevent further damage to the compressor. While you wait for a technician, keep your blinds closed, avoid using the oven, and use ceiling fans to keep air moving.
Our team is out on the road every day through extreme heat to get your cooling restored as quickly as possible.

08/24/2026

How do we pinpoint hard-to-find AC refrigerant leaks?
When your air conditioner loses refrigerant, the system struggles to cool your home efficiently. Locating the exact source of a leak inside a crowded attic or dark utility space used to be tricky, but modern electronic leak detectors make a huge difference.
Advanced tools like the INFICON D-TEK Stratus feature two essential modes:
Cloud Hunting Mode: Scans a broad area to detect refrigerant gas lingering in the air.
Pinpoint Mode: Fine-tunes sensitivity to lead technicians straight to the specific leaking joint or coil.
Features like adjustable sensitivity and audio headphone jacks help us work accurately even on noisy job sites. Precision diagnostic equipment ensures we locate and resolve issues fast.

08/20/2026

Have you noticed water spots around your ceiling vents or sweating ductwork in the attic? A common cause is improperly sealed duct connections.
When supply buckets and flex duct joints aren't sealed airtight, hot attic air meets cool conditioned air. This causes moisture to build up and condense, leading to water leaks, microbial growth risks, and wasted energy.
To solve this, our technicians seal all gaps around supply boxes using heavy-duty mastic sealant. We secure the inner air barrier with heavy-duty straps and ensure the outer insulation barrier is pulled tight and sealed to prevent sweating.
Proper duct sealing keeps your system running efficiently and protects your home from moisture damage.

08/19/2026

San Marcos Business Expo!

08/17/2026

When replacing or installing ductwork, proper sealing is essential for home comfort and efficiency.
Here is how proper ductwork installation protects your HVAC system:
Sealing supply buckets: Applying heavy-duty mastic sealant around supply boxes seals them tight against the sheetrock. This prevents cooled air from leaking into the attic and stops moisture buildup.
Understanding flex duct layers: Flexible ductwork features an inner liner that carries air, wrapped in thick insulation and an outer v***r barrier.
Preventing condensation: Clamping both the inner core and outer v***r barrier tightly prevents hot attic air from touching cool air, keeping ductwork from sweating.
Proper sealing keeps your system efficient and protects your ceiling from water damage.

08/13/2026

A common question we hear at SM Air is how many AC units a home actually needs.
Every house is different. When determining your needs, we typically look at:
Total square footage
Home layout and number of stories
Your specific cooling demands
If your home requires two units to stay cool, we can easily install them. If it only requires one, we will never pressure you to buy a second; we simply want to help you stay comfortable in your space.
If you are looking for a new system, we highly recommend the Trane XV17 multi-stage condenser. It is a fantastic unit that delivers reliable, efficient cooling. Give us a call today to see if it is the right fit for your home!

Address

3500 Highway 123
San Marcos, TX
78666

Opening Hours

Monday 8am - 5pm
Tuesday 8am - 5pm
Wednesday 8am - 5pm
Thursday 8am - 5pm
Friday 8am - 5pm
Saturday 8am - 5pm

Telephone

+15122121351

Website

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