Furnace Repair in San Antonio, TX — Gas, Electric & Propane Specialists
Locally Owned Since 2016 | Bilingual Techs (English / Español) | Bonded & Insured
Same-Day Furnace Repair That Names the Failed Part Before We Touch It
When your furnace quits in San Antonio, you don’t need a vague quote — you need someone who can tell you which part failed, why, and what it costs before any work starts. EMAX HVAC has been doing exactly that since 2016: component-level diagnostics on gas, electric, and propane furnaces across San Antonio, Stone Oak, Alamo Heights, Shavano Park, Terrell Hills, The Dominion, and Cordillera Ranch. No upsells. No franchise scripts. Just the actual problem and the honest fix.
Is Your Furnace Doing One of These? You Likely Need Furnace Repair
Most San Antonio furnace problems show up as one of six symptoms. If you’re seeing any of these, stop running the system and call us before damage spreads.
Furnace blowing cold air
The blower runs, but the air coming out of the vents is room temperature or colder. Usually a failed igniter, a tripped flame sensor, a closed gas valve, or a thermostat wired to the wrong terminal.
You hear the clicking of the ignition sequence, but no flame and no heat. Most often a worn-out hot surface igniter (a $35 part most San Antonio homeowners overpay for) or a dirty flame sensor.
The furnace fires up, runs briefly, shuts down, and repeats. Pressure switch issue, restricted airflow from a dirty filter, oversized unit, or a failing limit switch protecting the heat exchanger.
Banging on startup usually means delayed ignition (dangerous — gas pooling before lighting). Screeching points to a dry blower motor bearing or worn belt. Rumbling after shutdown suggests burner deposits.
No fan, no ignition, no thermostat response. Could be as simple as a tripped breaker, a blown low-voltage transformer, a dead control board, or a safety switch that locked out the system after a previous failure.
A healthy gas furnace burns blue. Yellow flame, soot around the unit, or a sharp chemical smell can mean incomplete combustion — and that means carbon monoxide risk. Shut the system off and call us immediately. See the safety section below.
How We Diagnose Your Furnace — The EMAX Process
Listen before we open the panel
Most techs unscrew the cover first. We start by listening to a startup cycle: ignition timing, blower delay, gas valve click, inducer ramp-up. The sequence tells us where the failure is before any tool touches the unit.
Test the actual failed component
We use a manometer for gas pressure, a multimeter for the igniter and flame sensor (microamp draw), and a static pressure probe for airflow. We don’t guess — we measure.
Show you the part and the reading
You see the failed part. You see the meter reading. You get the price for the repair and the price for replacing the unit if your furnace is past its useful life. Then you decide — no pressure scripts.
Repair on the spot when possible
Our trucks stock the parts that fail most often in San Antonio furnaces: igniters, flame sensors, capacitors, pressure switches, low-voltage transformers, and common thermostats. Most repairs finish in the same visit.
Component-Level Furnace Repair Services We Perform
Furnace igniter repair & replacement
Hot surface igniters fail every 3–7 years in San Antonio’s climate. We carry universal HSI replacements for Carrier, Trane, Lennox, Goodman, Rheem, York, Bryant, American Standard, and Amana — most replacements done in under 45 minutes.
Furnace blower motor repair & replacement
Whether it’s a single-speed PSC motor or a variable-speed ECM, we diagnose blower motor failures by capacitor reading, amp draw, and bearing test. We repair when feasible (capacitor swap, lubrication, wheel cleaning) and replace only when the motor itself has failed.
Furnace gas valve repair
A stuck or failed gas valve is a no-heat call that requires a licensed tech (TACLA158965E). We test inlet/outlet pressure, verify the valve coil resistance, and replace when needed with the correct gas valve for your furnace make and model.
Furnace heat exchanger inspection & service
A cracked heat exchanger is a CO leak waiting to happen. We inspect with a borescope and combustion analyzer. If it’s cracked, we’ll tell you honestly whether replacement of the part makes sense or whether replacing the furnace is the smarter long-term call.
Furnace control board replacement
Modern furnaces fail at the control board more often than people realize — a single capacitor or relay on the board fries and the whole system locks out with an error code. We diagnose by error code, board voltage testing, and replace with OEM or quality universal boards.
Furnace inducer motor replacement
The draft inducer pulls combustion gases through the heat exchanger and out the vent. When it fails, the pressure switch never closes and the furnace won’t fire. We replace inducer assemblies on most major brands.
Flame sensor cleaning & replacement
A dirty flame sensor is the #1 cause of “furnace lights then shuts off after 5 seconds.” Often a $0 fix with a quick cleaning. We replace only when oxidation is permanent
Furnace thermostat repair & rewiring
Bad thermostat, wrong wiring after a DIY install, or a failed C-wire transformer — we diagnose and either repair the existing setup or recommend a smart thermostat upgrade with proper wiring.
San Antonio Trusts EMAX HVAC for Furnace Repair
EMAX HVAC is a locally owned heating and cooling company based at 310 Roswell Canyon, San Antonio, TX 78245, serving homeowners across Bexar County since 2016. We are licensed (TDLR TACLA158965E), bonded, and insured, and our technicians work in both English and Spanish. Unlike national franchises that send rotating crews and read from upsell scripts, our team diagnoses your furnace at the component level — igniter, blower motor, gas valve, heat exchanger, control board — and quotes the actual repair before any work begins. That’s why San Antonio homeowners call us for furnace repair from Stone Oak to Alamo Heights and Shavano Park to The Dominion.
Safety First — When to Shut Off Your Furnace Before Calling
Before you do anything else, shut your furnace off at the thermostat and the gas valve if you notice any of the following:
- You smell rotten eggs or sulfur (natural gas leak — leave the house, call 911 and your gas company first, then call us)
- Your CO detector is going off or you feel dizzy, nauseous, or get headaches when the heat runs (carbon monoxide risk — leave the house, call 911)
- Yellow flame, soot, or sharp chemical smell from the unit
- Visible water leak from a high-efficiency furnace condensate line near the burner area
- Loud bang on ignition (delayed ignition — keep the system off until inspected)
Then call us at 210-920-1412. We’ll prioritize gas safety calls and route a tech same-day whenever possible.
Furnace Repair Across San Antonio and Surrounding Neighborhoods
We service furnace repair calls across San Antonio and the surrounding communities — including Stone Oak, The Dominion, Alamo Heights, Terrell Hills, Shavano Park, and Cordillera Ranch. Our trucks are based in San Antonio (78245), so most addresses inside Loop 1604 see same-day arrival, and Hill Country properties typically get next-morning service. If your zip is in Bexar County and your furnace is down, call us — we’ll give you a real arrival window before you commit.
Add Your Heading Text Here
Honest call: not every “no heat” problem is a furnace problem. If your home has a heat pump (common in newer San Antonio builds), the issue may be in the outdoor unit or the reversing valve — see our general heating repair page for heat pump diagnostics. If your furnace itself is fine but rooms are uneven or vents are weak, the issue is usually duct-related. We’ll tell you straight — if it’s not the furnace, we won’t sell you a furnace repair.
Furnace Repair Questions San Antonio Homeowners Ask
How much does furnace repair cost in San Antonio?
Most common furnace repairs in San Antonio fall between $150 and $650 — igniter replacement, flame sensor cleaning, capacitor swap, pressure switch, or thermostat. Major component repairs (blower motor, control board, inducer motor) typically run $400–$900. Heat exchanger replacement is the one repair where we’ll often recommend evaluating a full furnace replacement instead — we’ll show you both numbers honestly.
Why does my furnace blow cold air sometimes?
Three usual causes: (1) the thermostat fan setting is on “ON” instead of “AUTO,” so the blower runs even between heating cycles; (2) the flame sensor is dirty and the burner shuts off after a few seconds; (3) the limit switch is tripping due to airflow restriction. We diagnose which one in a single visit.
Should I repair or replace my furnace?
Rule of thumb in San Antonio: if your furnace is under 12 years old and the repair is under 30% of replacement cost, repair. If it’s 15+ years old, has had multiple failures in 2 years, or needs a heat exchanger or control board, get a replacement quote alongside the repair quote. We give you both numbers — no pressure either way.
Do you repair furnaces on weekends?
Yes. EMAX HVAC offers same-day and weekend furnace repair in San Antonio for active no-heat calls. Call or text 210-920-1412 — we confirm availability and give you a real time window before dispatch.
Why does my furnace keep tripping the breaker?
A furnace that trips its breaker usually has either a shorted blower motor, a failed control board, or a wiring issue. Don’t keep resetting the breaker — that’s an electrical fire risk. Shut it off and call us for a proper diagnosis.
How long does a furnace igniter last?
Hot surface igniters typically last 3–7 years in San Antonio. They’re a wear part — every time the furnace fires, the igniter heats to ~2,000°F and cools. Eventually it cracks. If yours has failed twice in the same year, the issue is usually upstream (gas pressure, voltage to the igniter, or a flame sensor problem) — not the igniter itself.
Do you work on all furnace brands?
Yes. We repair Carrier, Trane, Lennox, Goodman, Rheem, York, Bryant, American Standard, Amana, Payne, and most other residential and light-commercial furnace brands sold in San Antonio over the past 25 years.
Are your technicians licensed and insured?
Yes. EMAX HVAC operates under TDLR license TACLA158965E and is fully bonded and insured. Every tech we send to your home is trained on gas furnace safety, combustion analysis, and component-level diagnostics.
Ready to Get Your Furnace Fixed Today? Call EMAX HVAC for Furnace Repair
If your furnace is down or acting up, don’t wait for the next cold snap. Call EMAX HVAC for honest, component-level furnace repair across San Antonio.