Your house is at 88 and climbing, and the outdoor unit is either silent or blowing air that feels like a hair dryer. In San Antonio that gets uncomfortable fast, because in a heat event the overnight low stalls near 75 and the house never gets a chance to dump what it gained all day.
Start here, in the first ten minutes
Three checks, no tools.
Check the thermostat: set to COOL, fan on AUTO, batteries good. Open the panel and look for a tripped air handler or condenser breaker. Then pull the filter and hold it up to a light.
If you see ice on the copper lines or the indoor coil, shut the system off at the thermostat and switch the fan to ON. A frozen system that keeps running sends liquid refrigerant back to a pump built for gas.
What actually breaks when the heat holds for days
Sustained load takes out the cheap parts first. Run capacitors swell or drift out of spec. Contactor points burn. Compressor overloads open when head pressure climbs past what the unit can shed into 103 degree air. Most of what we replace during a stretch of triple digits is smaller than your fist.
Airflow is where the expensive damage happens. In the diagnostic guideline David Springer and Bill Dakin wrote for the Department of Energy’s Building America program, airflow below 200 cfm per ton “can lead to coil icing and greatly shorten compressor life.” Across the field studies that guideline reviews, two thirds of homes sat below the 350 cfm per ton minimum.
Charge is the other half. Those same studies cover 4,168 air conditioners, and 72 percent carried an improper refrigerant charge. Undercharge drops coil temperature, ice forms, and the ice chokes the airflow that would have melted it.
Why a tripped breaker is a symptom and not a repair
Reset it once. If it goes again, stop. A breaker that trips twice in a row is reporting a real fault, and it’s doing its job by staying off.
A condenser tripping on a 103 degree afternoon usually means one of two things. Either the compressor is pulling locked rotor amps, or the capacitor failed and the motor stalls trying to start. Flipping that breaker back on ten times is how a repairable fault turns into a replaced compressor.
CPS Energy asks customers to set thermostats 2 to 3 degrees higher between 3 and 7 p.m., when demand peaks and your condenser is dumping heat into the hottest air of the day. Tired capacitors quit inside that window.
Heat doesn’t invent new problems. It finds the part that was already worn out and makes you deal with it on the worst possible afternoon.
Keeping the house livable while you wait
If your AC died in a heat wave, the next few hours are about slowing down how fast the house gains heat.
- Close every blind and curtain on west and south glass, and shut doors to unused rooms.
- Shut off the oven, the dryer, and anything else with a heating element.
- Move cooking outside or skip it. A stovetop dinner can add several degrees to a house with no cooling.
- Run a fan for air movement, not for cooling. A fan moves heat off skin without lowering the room temperature.
- Pull the filter if it’s loaded, so the blower isn’t fighting it when the system comes back.
- Leave the thermostat set where you want it and stop cycling it. Repeated restarts on a faulted system do damage.
- If the house isn’t holding, go somewhere air conditioned for the afternoon. The city publishes a list of public cooling locations.
We’re a Monday through Saturday shop, 7 a.m. to 7 p.m., not an overnight service. If your system quits Saturday evening, plan on getting somewhere cooled for the weekend rather than waiting it out, and call or text us first thing Monday.
Heat makes people sick, and that part is outside our lane. The CDC publishes what to watch for and who is most at risk. Confusion, slurred speech, or a very high temperature is a 911 call, not a wait-and-see.
The same breakdown looks different by neighborhood
Housing stock decides how a failure shows up, and this city stacks four eras of it inside ten miles.
Woodlawn Lake and the 1920s bungalows
Abel lives out here, so these are the streets we work most. Wood frame Craftsman houses, thin walls, and central air retrofitted into homes that were never built for ducts. Being minutes away is why same-day here usually means before dinner. Those retrofitted runs were tight from the start, so a frozen coil is the first thing we check around the lake. Kill the system the moment you see frost. Conservation district rules also limit where outdoor equipment can sit, so replacement talk starts with placement.
Terrell Hills and one of the city’s oldest enclaves
Most of this stock predates central cooling, and what we find is a modern condenser bolted onto retrofitted duct with a return nobody enlarged. Look behind that return grille before you accept any diagnosis, because a starved return will mimic a failing system. Be skeptical of anyone answering with more tonnage, too. Bigger equipment against the same restricted return ices up faster, not slower.
Castle Hills and the 1950s ranches
Long, low houses on quarter and half acre lots, usually on a single stage system sized before somebody enclosed the garage. The sprawl means the far end gives up first, and people read that as a total breakdown when it’s really a system out of capacity at 103. Feel a register near the air handler. Cold air there with an 85 degree back bedroom points to distribution, and the fix is zoning.
What we test before anyone brings up replacement
A real diagnosis is a sequence of measurements. What gets checked on a no-cooling call:
- Capacitor under load. Microfarad rating tested while the motor tries to start, never a look at the can.
- Compressor amp draw. Locked rotor amps say whether the compressor is stuck, weak, or starved.
- Superheat and subcooling. The only honest read on charge. A gauge glance is not a charge check.
- Temperature split and static pressure. Where undersized returns and crushed flex duct get caught.
- Both coils. A fouled evaporator strangles airflow and a dirty condenser drives head pressure up.
- Drain line and float switch. A full pan trips the safety and shuts everything down on purpose.
We spelled it all out in what a real AC diagnostic includes. Everything else sits on our HVAC repair contractor in San Antonio page.
When the air conditioner isn’t really the problem
Sometimes the equipment is fine, and the house is losing heat anyway. A superheated attic radiating down through insulation that was skimpy when it went in. A system carrying two rooms it was never sized for. A filter untouched since March, which the Department of Energy answers plainly: change it every month or two during cooling season.
We’re family-owned, licensed in Texas as a Class A air conditioning and refrigeration contractor with the Combined endorsement, EPA 608 certified, and BBB A+ rated. We’d rather charge you for a capacitor than sell you a system you don’t need yet. Every repair carries a 90-day warranty, and financing is available if the honest answer runs big.
Call or text 210-763-4698. We run same-day repairs when the part is on the truck, Monday through Saturday, 7 a.m. to 7 p.m.