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San Antonio Furnace Repair
The Furnace That Fails Here Is the One Nobody Has Looked At
A San Antonio furnace does not wear out from overuse. It fails from sitting. Between March and November it does nothing while the attic around it bakes at 120 degrees, and that heat is hard on control boards, wiring insulation and the plastic parts of a pressure switch. Dust settles on the burners. The flame sensor grows a film of oxide. Then a norther rolls through, the thermostat calls for heat, and the ignitor glows, the burners light, and the furnace shuts down 30 seconds later because the sensor cannot see the flame. That sequence is the most common no-heat call we take in this city.
Gas furnaces are common in San Antonio homes from the historic neighborhoods to Stone Oak, usually in an attic or a hall closet. In the all-electric subdivisions across the northeast side and out toward Cibolo and Converse, the “furnace” is an electric air handler with heat strips, and its failures are sequencers, limit switches and burned contacts. We repair both, and we have since 1999, dispatching from our office on Wye Drive. In February 2021 we learned again how much a working furnace matters when the temperature does not climb above freezing for days.
The mechanics of a furnace, from the ignition sequence to why a cracked heat exchanger is a shut-it-down problem, are on our furnace repair page. Here is what a San Antonio winter does to one.
- Gas and electric furnaces Natural gas furnaces in attics and closets, and electric furnaces with heat strips in all-electric homes.
- Safety check on every gas call Heat exchanger, venting and carbon monoxide are checked before we chase the fault you called about.
- Price first, no surprise fees A written quote honored for 72 hours, the same at 2 a.m. during a freeze as on a mild afternoon.
What It Is Telling You
Furnace Symptoms San Antonio Homeowners Report
Most of these are an hour and a part. One or two are a leave-the-house-now problem. Here is which is which.
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Lights, runs half a minute, shuts off, tries again
A dirty flame sensor, almost every time after a long idle season. A quick fix if you call before it wears out the ignitor.
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Clicking, but no ignition
A failed hot-surface ignitor, a stuck gas valve or a pressure switch that will not close. All common after a hot attic summer.
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Blower runs, air stays cold
On a gas furnace, the burners are not lighting. On an electric furnace, the heat strips or their sequencer have failed.
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Carbon monoxide alarm, headaches, or a yellow lazy flame
Get everyone out and call from outside. This can be a cracked heat exchanger or blocked vent, and it is the one furnace fault that can hurt you.
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Runs a few minutes, quits, repeats all night
Short cycling from a clogged filter, a tripping limit switch or a furnace that is too big for the house.
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A bang when it lights, or a squeal when it runs
Delayed ignition from dirty burners, or a blower motor bearing on its way out. Both worth a call before the next front.
What We Repair
Furnace Repairs Across the San Antonio Area
Attic furnaces, closet furnaces, package units on the roof and electric air handlers, in homes of every age.
- Ignition and flame sensing Hot-surface ignitors, flame sensors, pilot assemblies and the boards that sequence them.
- Pressure switches and inducer motors The parts that prove the vent is clear before the gas valve opens. When they fail, the furnace refuses to light for good reason.
- Heat exchanger inspection Checked on every gas furnace call. A cracked exchanger is a replacement, not a repair, and we will show you why.
- Electric furnace heat strips Strips, sequencers, limits and contactors in the all-electric air handlers common on the northeast side.
- Blower motors and capacitors The same blower runs your cooling all summer, so by December it has earned a look.
- Thermostats and wiring Low-voltage faults and thermostats that call for cooling in January. More common than you would think after a DIY thermostat swap.
The Visit
How a Furnace Repair Call Goes
Safety, then diagnosis, then a price, then the fix. In that order, every time.
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Call any hour
If you smell gas or a CO alarm is sounding, get out first and call from outside. Otherwise tell us what the furnace is doing and we will schedule the soonest window.
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Safety inspection
Heat exchanger, venting, gas connections and combustion. A furnace that is unsafe gets shut down and explained, not patched.
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Diagnosis and written price
We find the fault, show you the failed part, and give you a quote honored for 72 hours. If replacement is smarter, you get those numbers too.
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Repair and verify
Full heating cycle, temperature rise checked, CO tested at the registers. Backed by the Home Comfort Guarantee.
Current Specials
Save on the work your home needs most.
San Antonio
HVAC
25% Off Select Air Purifiers & Filters
Expires 12/31/2026
San Antonio
HVAC
Up To $2,500 OFF Full HVAC System!
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San Antonio
HVAC
Buy a Complete HVAC System, Get a Furnace FREE!
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San Antonio
HVAC
Last Chance HVAC Tune-up $68
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Both Locations
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Up to $200 off Duct Cleaning
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Both Locations
HVAC
$99 Furnace Tune-Up
Expires 12/31/2026
Furnace Out in San Antonio?
We are staffed through every cold front, and a freeze does not change the price.
What Our Customers Say
Don't just take our word for it — hear from our satisfied customers
★★★★★
Our 18 year old HVAC system finally gave out this past week, so we reached out to Radiant to see what could be done. They sent a tech out named Bryan the same day, and he did a great job looking over the entire HVAC system. He was friendly and helpful in explaining everything that he saw, and our options moving forward. We decided to replace the entire system, so we met with Jacob (same day thankfully) to find the best HVAC system for our needs. Jacob was friendly, professional, and did a great job explaining the different options on offer. Radiant was able to set-up next day install, which was much appreciated, because the temps were still going to be cold in the coming days.
The install team consisted of Carlos and Pablo, who were very courteous and professional, and were kind enough to answer any questions I had regarding the install. They did a great job installing our new HVAC system, and were tidy which is always appreciated! Before they left, they explained everything that had been done, and showed me photos of the work.
Our entire experience from start to finish was great. I appreciate that they send photos of who is coming to your home too. Friendly, kind, professional team members, and good work all the way around. Thanks Radiant!
The install team consisted of Carlos and Pablo, who were very courteous and professional, and were kind enough to answer any questions I had regarding the install. They did a great job installing our new HVAC system, and were tidy which is always appreciated! Before they left, they explained everything that had been done, and showed me photos of the work.
Our entire experience from start to finish was great. I appreciate that they send photos of who is coming to your home too. Friendly, kind, professional team members, and good work all the way around. Thanks Radiant!
★★★★★
This is the first time I’ve used radiant my neighbor recommended them…. I called them today and they set me up an appointment on the same day. I was totally shocked at that and the service call was only $39!!…. Highly recommend them Danielle showed up and he was a great guy and he put up with all my wishy-washiness and I had to hurry him because I was heading to church and he got caught in a lot of traffic getting here he even would’ve installed the part that broke but I Didn’t have the time tonight….. He was patient with me and just told me to call the office first thing in the morning and get a service call set up…. Thank you so much Radiant!!….
With another cold front coming in tomorrow now I just hope they can get me scheduled for a separate call tomorrow but I have a feeling they will. They are such a great company!!😊😊
With another cold front coming in tomorrow now I just hope they can get me scheduled for a separate call tomorrow but I have a feeling they will. They are such a great company!!😊😊
★★★★★
My unit had been acting funky for a bit and then decided it would shed its mortal coil and go to the next life. I called an another company lets call them company A since I had a warranty with them thinking I could save a few bucks. They showed up 2 hours late of given window. Warranty didnt cover any of the perceived issues ( not really their fault, maybe). Double billed me (why pay 700 for a service call when you can pay 1400!!! ie: they ran my card twice) and then even though issue still wasnt fixed wanted to upsell me some more for close to 3k or get another sweet unit for an overpriced amount.
I'll admit I was getting desperate. Do I let the giant commercial bad guys win? Give them all my money I could be using on fishing gear? My neighbor happens to work at Schmidt Mechanical Group (shout out to Jared) and got me in touch with their service technicians for a 2nd opinion. ENTER Richard Moreno. Showed up at the beginning of time window. Diagnosed the multiple issues in a timely manner. Explained to me what was going on and why and hand held me through what needed to be done now and what to expect in the future. Worked on both of my units. My bill came to a FRACTION of what was recommended by company A. Mr. Moreno was very professional, kind, and honest. As a first time home owner whos been bamboozled by companies like company A, Schmidt Mechanical Group just gained a customer for life. Look forward to doing more business with them and their techs are awesome. Dont be like me and use company A first. Use this company.
I'll admit I was getting desperate. Do I let the giant commercial bad guys win? Give them all my money I could be using on fishing gear? My neighbor happens to work at Schmidt Mechanical Group (shout out to Jared) and got me in touch with their service technicians for a 2nd opinion. ENTER Richard Moreno. Showed up at the beginning of time window. Diagnosed the multiple issues in a timely manner. Explained to me what was going on and why and hand held me through what needed to be done now and what to expect in the future. Worked on both of my units. My bill came to a FRACTION of what was recommended by company A. Mr. Moreno was very professional, kind, and honest. As a first time home owner whos been bamboozled by companies like company A, Schmidt Mechanical Group just gained a customer for life. Look forward to doing more business with them and their techs are awesome. Dont be like me and use company A first. Use this company.
Maintenance Membership
Join the Care Club
Home maintenance for $9.99 a month.
Care Club members get two HVAC tune-ups and a plumbing safety inspection every year, priority scheduling, no dispatch fees — ever — and 5% off every repair.
- Priority scheduling
- Seasonal HVAC tune-ups
- Annual safety inspection
- Exclusive member discounts
- Free dispatch on repairs
- No long-term contracts
San Antonio Furnace Repair Questions
My furnace worked last winter and will not light now. What happened while it sat?
A San Antonio attic in July is a hard place to spend the summer. Heat degrades the control board, dries out wiring insulation and stresses the plastic diaphragm in the pressure switch. Dust settles on the burners and the flame sensor, and the sensor oxidizes so that when the burners finally light, the board cannot confirm it and shuts the gas off. Rodents occasionally chew wiring or block a vent. None of this announces itself until the first cold night. The good news is that most of these are quick repairs with parts we carry, and a fall tune-up catches nearly all of them. That visit is one of the two annual HVAC tune-ups included with Care Club.
Is it safe to keep running a furnace that smells a little when it starts?
A dusty, slightly burnt smell for the first hour of the season is normal; it is dust burning off the heat exchanger. Two smells are not. A rotten-egg gas odor means a leak: leave, and call from outside. A sharp electrical or plastic smell that persists means something is overheating, and the furnace should be shut off at the switch until it is inspected. Any headache, nausea or a carbon monoxide alarm while the furnace runs is a reason to get everyone out immediately. We check the heat exchanger and venting on every gas furnace call because a crack you cannot see is the fault that matters most.
Repair or replace a 20-year-old furnace in a Stone Oak house?
It depends on what failed. A 20-year-old furnace with a bad ignitor or flame sensor is worth repairing; those are inexpensive parts, and the furnace may have more winters in it. A 20-year-old furnace with a cracked heat exchanger is a replacement, because the exchanger is the furnace and the repair costs nearly as much as new equipment. In between, look at the pattern: if this is the second or third repair in a few years, replacement usually wins. In a Stone Oak home the air conditioner is likely the same age, so it is worth pricing a matched system or a heat pump while you are at it. We give you both sets of numbers in writing; our furnace replacement page explains the process.
My house is all-electric. Do you repair electric furnaces too?
Yes. A large share of homes on the northeast side, in Converse, Universal City, Schertz and Cibolo, and in newer subdivisions across the metro heat with an electric air handler and heat strips, sometimes paired with a heat pump and sometimes with a straight air conditioner. The parts that fail are different from a gas furnace: heat strip elements burn out, sequencers stick, limit switches trip, and contacts pit and burn. We stock the common ones. If your electric furnace is paired with a plain air conditioner rather than a heat pump, it is worth knowing that a heat pump would heat the house for far less each winter; our San Antonio heat pump page explains why.
*Offers cannot be combined with other promotions or applied to dispatch fees. No cash value. Must present offer at time of service. Call for details.
