How much does an AC contactor cost in San Antonio?
$185 to $320 installed, depending on the amp rating (30A or 40A) and whether the disconnect box needs cleaning or the wire lugs need repair. Service call is waived with the repair.
San Antonio · AC Contactor Repair · Family-Owned Since 1996
AC Running Nonstop or Won't Turn On at All? Check the Contactor.
A contactor is the relay switch that tells your outdoor unit when to run. When the contacts pit and burn — and they always do, eventually — your AC either won't start or won't shut off. Most jobs done in 45 minutes.
Typical price
$185–$320 installed
Time to fix
30–60 minutes
Urgency
High — risk of compressor damage
In plain English — what's going on with your ac contactor
The contactor is a small black box inside your outdoor disconnect that physically closes a circuit every time your thermostat calls for cooling. It's basically a heavy-duty light switch that flips on and off thousands of times every summer.
Every time those metal contacts open and close they create a tiny arc. Over 4 to 6 San Antonio summers, that arcing pits and burns the contact surfaces until they either weld shut (AC runs nonstop) or won't make contact at all (AC won't start, even though the thermostat is calling).
The contactor and capacitor sit right next to each other inside the disconnect box. When one fails, the other is usually right behind it — we'll always test both while we're in there.
What it costs in San Antonio
$185–$320 installed — Includes a quality 30-amp or 40-amp contactor, labor, and a full electrical check. Our $59 diagnostic is waived when you approve the repair, so you only pay for the fix itself.
Symptoms you'll notice at home
If two or more of these sound familiar, it's probably your ac contactor.
Outdoor unit runs constantly, even when thermostat is off
AC won't start even though the thermostat is calling for cool
Loud humming or buzzing from the outdoor disconnect
Clicking sound when the thermostat calls for cooling, but nothing starts
You can see pitted, burned, or melted contacts when the disconnect cover is off
Ants or wasps nesting inside the disconnect (very common in San Antonio)
Why ac contactors fail in San Antonio
- Normal wear — every switch cycle arcs a little. 4 to 6 years of San Antonio summers is the typical lifespan.
- Ants. Specifically, crazy ants and Texas leaf-cutter ants love getting into the disconnect and shorting the contacts. We see this constantly.
- Voltage surges from CPS Energy storms welding the contacts shut.
- An undersized contactor from a previous repair (e.g. a 30A on a system that draws 32A).
- Failed capacitor next to it overloading the contactor.
How we diagnose and replace it
Here's exactly what a Carnes and Sons tech does at your house — no mystery, no upselling.
- 1
Cut power and inspect the contacts
We pull the disconnect, open the access panel, and look at the contact surfaces. Pitted, blackened, or welded contacts are an automatic replace — they won't get better.
- 2
Test the coil voltage and contact resistance
With the meter we check that the 24V control voltage is reaching the coil correctly and that the closed contacts read less than 0.5 ohms. Anything higher means heat and impending failure.
- 3
Install a quality match — 40A even on a 30A system
We size up to a 40-amp Mars or Packard contactor for longevity. The extra capacity costs about $8 wholesale and easily doubles the life. We seal the disconnect box against ants while we're in there.
- 4
Verify and clean up
Re-energize, watch a full cool cycle, measure inrush and running amps on the compressor, and make sure the contactor pulls in clean and crisp. Then we show you the old burned part.
What Your Neighbors Are Saying
Get Your AC Contactor Diagnosed Today
Tell us what's happening. We'll text you back in minutes — no call center, no robo-calls.
AC Contactor questions San Antonio homeowners actually ask
What's the difference between a contactor and a capacitor?
The capacitor stores electricity and kicks the motors into starting. The contactor is the switch that connects high voltage to those motors when the thermostat calls. They sit side-by-side in your outdoor unit. Both wear out, often within a year or two of each other.
Why does my AC keep running even when the thermostat is off?
Almost always a contactor with the contacts welded shut from arcing. The thermostat is telling the unit to stop, but the switch is physically stuck closed. Cut power at the disconnect or breaker right away — running the compressor nonstop will burn it out in a day or two.
Can ants really kill my AC?
Yes — and they do, constantly in San Antonio. Crazy ants are attracted to the electrical fields in the disconnect, get crushed between the contacts, and short out the unit. We seal the box and treat around the slab as part of every contactor job.
How long does a contactor last?
A factory 30A contactor lasts 4 to 6 summers in San Antonio. A 40A upgrade lasts 8 to 10. Annual maintenance and keeping ants out adds years.
Should I just replace the capacitor and contactor together?
If both are 4+ years old, yes — we strongly recommend it. The combined job adds about $80 and you save a second service call later. We'll always show you the readings on both before recommending.
Can you come today?
Yes. Contactor calls are a daily occurrence for us in summer — we keep same-day slots open. Text (210) 600-5091.
Do you warranty the part?
5 years on the contactor itself, 1 year labor. If the new contactor fails inside 5 years, we replace it free.
Serving ac contactor repairs across the greater San Antonio area
We're based in Stone Oak and roll trucks across San Antonio and the surrounding Hill Country every day.
Carnes and Sons Air Conditioning
License TACLB29435E · Family-Owned Since 1996
401 E Sonterra Blvd Suite 375
San Antonio, TX 78258(210) 600-5091
San Antonio, TX 78258(210) 600-5091
Mon–Sat: 7AM – 8PM · Emergency same-day service
Cities & neighborhoods we serve
San Antonio · Stone Oak · Alamo Heights · Hollywood Park · Hill Country Village · Shavano Park · Castle Hills · Leon Valley · Helotes · Boerne · Fair Oaks Ranch · Bulverde · Timberwood Park · Garden Ridge · Schertz · Cibolo · Selma · Universal City · Live Oak · Converse · Windcrest · New Braunfels
Talk to a real person about your ac contactor
No call center. The owner or one of his sons picks up.
(210) 600-5091