QUICK ANSWER
Three HVAC problems are emergencies no matter what the calendar says: a gas smell, a burning or electrical smell, and a carbon monoxide alarm. Those are utility and 911 calls before they are HVAC calls. Everything else comes down to two questions — who is in the house, and what month it is. A system that quits in August with an infant, an older parent or someone with a heart or lung condition at home is urgent tonight. The same failure in January is a comfort problem that can wait for morning. Water running from a ceiling is always same-day, because the damage grows by the hour. Castle Air Conditioning & Heating offers same-day service across southwest Houston.
Almost every Houston homeowner has stood in a warm hallway at eleven at night wondering whether this is a call-now problem or a call-tomorrow problem. It is a fair question, and the honest answer is that most HVAC failures are not emergencies. A few genuinely are, and a couple are not really HVAC calls at all.
Here is how we sort them, in the order we would ask you about them on the phone.
On this page
Three things that are not HVAC calls at all
Start here, because these three outrank every other question on this page. If any of them is happening, stop reading and make the call.
Call before you call us
You smell gas. Get everyone outside first. Do not flip switches, do not use the garage door opener, and do not use your phone until you are out of the house. Then call your gas utility, which is CenterPoint Energy across most of the Houston area, or call 911.
A carbon monoxide alarm is sounding. Everyone outside, then 911. Carbon monoxide is colorless and odorless, and a sounding alarm is not something to investigate yourself.
You see smoke, or smell burning plastic and see scorching. Shut the system off at the breaker if you can reach it safely, and call 911 if there is any smoke or visible damage.
Once the house is safe, an HVAC call is the right next step. We can find out why a heat exchanger or a wiring fault caused it. We are not the first call while it is still happening.
What counts as a real emergency
After safety, a genuine emergency is one of two things: it is getting worse while you wait, or someone in the house cannot tolerate the conditions. That is the whole test.
911
Gas, CO, smoke
Life safety before repair
Tonight
Getting worse
Water, repeat breaker trips, heat risk
Same day
Summer heat
The house keeps climbing until sunset
Next day
Stable
Nothing worsens while you sleep
Four tiers, most urgent first. Everything on this page sorts into one of them.
The house is hot and someone in it is vulnerable. Infants under one, adults over sixty-five, pregnant women, and anyone with a heart or lung condition or on medication that affects temperature regulation all lose the ability to shed heat well before a healthy adult does. In a Houston summer an indoor temperature climbing past 90 degrees is a medical question, not a comfort one. We wrote about how hot is too hot inside a Houston house in more detail.
Water is actively running. A stain on a ceiling can wait. Water coming through a ceiling cannot, because the cost curve is steep and it runs on its own schedule. Drywall, insulation and framing all absorb it, and standing water in an attic invites biological growth that is far more expensive to deal with than the repair that caused it. Shut the system off and call. This is usually a clogged condensate drain line, which is a straightforward fix when someone gets to it quickly.
The breaker keeps tripping. Resetting a breaker once is reasonable. Resetting it a second time is not. A breaker that trips repeatedly is doing its job, and forcing it back on is how a fault becomes a fire.
No heat during a hard freeze. Houston does not get many, but when we do, an unheated house is a burst-pipe risk rather than a blanket problem. That moves it into emergency territory for reasons that have nothing to do with comfort.
What can safely wait until morning
Most of what people call about at midnight is genuinely fine to handle in daylight, and waiting usually gets you a calmer appointment and a technician who is not working by flashlight.
- One room is warmer or cooler than the rest, but the system is running
- A new rattle or hum that is not a grinding or screeching noise
- A blank thermostat screen in a house that is still comfortable — try fresh batteries first
- The outdoor unit is running but the house is cooling slowly
- A slow drip into the condensate pan that the pan is still holding
- Your bill jumped and you want to know why
- Ice on the refrigerant line, once you have switched the system off and let it thaw
That last one surprises people. Ice usually means airflow or refrigerant trouble, and running the system while it is frozen does more harm than leaving it off overnight. Switch it off, let it thaw, and book a look in the morning.
Why the month changes the answer
The same failure is a different problem in August than it is in December. This is the part homeowners underrate, and it is the easiest way to decide whether you are calling tonight or tomorrow.
Houston’s normal high temperature, month by month
Average daily high at Bush Intercontinental, 1991 to 2020 climate normals from the National Weather Service Houston office. Red months are when losing cooling becomes a safety question rather than a comfort one.
June through September, the outdoor average alone sits at or above 90 degrees. Indoors, with humidity, it feels considerably hotter than that.
From June through September a house without cooling does not settle at a tolerable temperature. It keeps climbing until the sun goes down, and the humidity we carry here means the air feels well above whatever the thermometer says. Those are the months when a failure is worth a same-day call even if nobody in the house is in a high-risk group.
From November through March, the same breakdown is an inconvenience. The exception is a hard freeze, when the question stops being comfort and becomes whether your pipes survive the night.
The whole thing on one page
If you want one place to look at eleven at night, this is it.
| What is happening | How fast | Why |
|---|---|---|
| Gas smell, carbon monoxide alarm, smoke or scorching | Call 911 or your gas utility now | This is a life-safety call before it is a repair call |
| Breaker trips again after one reset | Tonight | A repeating trip is a fault, and forcing it is how faults become fires |
| Water running through a ceiling or pouring from the air handler | Tonight | Damage compounds hourly and spreads into drywall, insulation and framing |
| No cooling, June to September, with an infant, an older adult or someone with a heart or lung condition at home | Tonight | Indoor heat becomes a medical risk well before it becomes unbearable |
| No heat during a hard freeze | Tonight | Burst pipes, not comfort |
| No cooling, June to September, healthy adults only | Same day | The house will keep climbing until sunset, but you have hours rather than minutes |
| Grinding or screeching from the outdoor unit | Same day, system off | Running it while it sounds like that turns a repair into a replacement |
| Ice on the line set or coil | Next day, system off to thaw | Running a frozen system causes the damage, so switching it off is the fix for tonight |
| One room off, odd new noise, high bill, slow cooling, blank thermostat in a comfortable house | Next business day | Nothing is getting worse while you sleep |
What to do while you wait
Whatever you decided above, a few things help between now and when a technician arrives.
If the cooling is off and the house is climbing
Close the blinds on any window the sun is hitting, move everyone to the lowest floor, and drink water before you feel thirsty. Above 90 degrees indoors a fan moves hot air over you rather than cooling you, so do not rely on one to keep a vulnerable person safe.
If water is involved, switch the system off at the thermostat first. That stops the coil producing more condensate while you wait. Photograph the damage before you mop it up, because your insurer will want to see it.
If anything smells like burning, shut the system off at the breaker and leave it off. Do not run it again to check whether the smell comes back.
If the system is iced up, switch it off and set the fan to on. That circulates house air across the coil and thaws it faster than leaving everything off.
When you do call us, it helps to know the age of the system, what changed before it failed, and whether the outdoor unit is running. Those three answers usually tell us what to bring.
Castle Air Conditioning & Heating has been serving southwest Houston since 1975, and we offer same-day service. If you are weighing up a call right now, our emergency and same-day AC repair page explains how we handle after-hours work and what happens when you call.
Frequently asked questions
Is my AC not working an emergency?
Usually not on its own. It becomes one if the house is climbing during a Houston summer and someone in it is an infant, over sixty-five, pregnant, or living with a heart or lung condition. It is also an emergency if the failure comes with water, a burning smell or a breaker that keeps tripping. A healthy household in October can wait for a morning appointment.
What is considered an HVAC emergency?
Anything that is getting worse while you wait, or that the people in the house cannot safely tolerate. In practice that means gas smells, carbon monoxide alarms, burning smells, repeated breaker trips, water running through a ceiling, no cooling in summer heat with a vulnerable person at home, and no heat during a hard freeze.
Should I call an HVAC company in the middle of the night?
If the situation is on the emergency list above, yes. If it is on the wait list, you will generally get a better outcome in the morning, when a technician can see the whole system in daylight and parts suppliers are open. Nothing on the wait list gets worse overnight.
Is a frozen AC unit an emergency?
No, but it does need you to act tonight. Switch the system off so it can thaw and set the fan to on. Running a frozen system is what causes the expensive damage, so turning it off is the emergency step. Book a technician for the next day to find the airflow or refrigerant cause.
Is water leaking from my AC an emergency?
It depends on where it is going. A slow drip the condensate pan is still catching can wait. Water coming through a ceiling or running down a wall cannot, because the damage spreads into drywall, insulation and framing by the hour, and standing water in an attic invites biological growth. Switch the system off and call the same day.
Is no heat an emergency in Houston?
Rarely, because our winters are mild. Houston’s normal high sits in the low sixties in January. The exception is a hard freeze, when an unheated house becomes a burst-pipe risk. During a freeze warning, treat no heat as urgent even if the house still feels bearable.
Does after-hours service cost more?
After-hours rates are different from standard business-hours rates. We will tell you what applies to your call before we dispatch anyone, so there is no surprise when the technician arrives. If you are on our Set It and Forget It Assurance Plan, plan holders receive a discount on repairs.
Real homeowners, real service
Houston homeowners keep asking for our technicians by name.
Google Reviews
4.9
★★★★★
Based on 200 reviews
