AC Repair in Houston
QUICK ANSWER
Castle Air Conditioning & Heating repairs air conditioners across southwest Houston, Fort Bend County and the Bay Area. We work on all makes and models, not only the brands we sell, and our technicians are NATE-certified. Call in the morning and we will usually reach you the same day. There is a diagnostic fee, we tell you what a repair costs before we start it, and you decide. Call or text (713) 667-7606.
If it is an emergency, do not read on
Water coming through a ceiling, a burning smell, a breaker that trips repeatedly or a hot house with vulnerable people in it needs a phone call now, not a web page. See emergency and same-day AC repair, or call (713) 667-7606. We answer 24/7.
What your air conditioner is telling you
Most people describe the symptom rather than the fault, which is exactly right. Here is what the common ones usually mean, and what is worth doing before you call.
| What you are seeing | What it usually means | What to do first |
|---|---|---|
| Running, but the air is warm | Low refrigerant, a failing compressor, or a dirty outdoor coil. Warm air with the system still running is the most common call we take. | Check the filter and the outdoor unit for debris, then call. Do not keep running it if the outdoor fan is not spinning. |
| Will not turn on at all | A tripped breaker, a dead thermostat battery, a blown capacitor, or a condensate float switch that has cut the power. | Check the thermostat is on COOL and set below room temperature, check the batteries, then check the breaker. |
| Cools, but never reaches the set temperature | Usually a system struggling against low refrigerant, a dirty coil or restricted airflow. Sometimes a system that is simply undersized for the house. | Change the filter, open closed vents, and note what time of day it loses ground. |
| Ice on the unit or the refrigerant line | Restricted airflow or low refrigerant. The coil gets too cold and condensation freezes on it. | Set the system to OFF and the fan to ON so the coil thaws. Do not chip at the ice. |
| Water around the indoor unit, or a stain on a ceiling | A blocked condensate drain. In Houston this is the single most common summer problem. | Turn the system off at the thermostat. See how to clear a clogged drain line. |
| Turning on and off every few minutes | Short cycling. Often an oversized system, a refrigerant problem, or a thermostat in a bad spot. | Worth a diagnosis. Short cycling wears a compressor out faster than almost anything else. |
| Grinding, screeching or banging | A failing motor or compressor. Loud mechanical noise is not something to wait on. | Shut it down at the breaker and call. |
| Cool but clammy, or a musty smell | The system is handling temperature but not moisture, and there may be biological growth on the coil or in the drain pan. | Have the coil, drain and airflow checked together rather than one at a time. |
| One room never cools | Duct leakage, poor balancing or a zoning fault, more often than an equipment problem. | Note which rooms and at what time of day. It helps us find it faster. |
What a repair visit actually involves
A diagnosis is a test, not a guess. A NATE-certified technician measures temperatures and pressures across the system, checks refrigerant charge and airflow, and tests the electrical components rather than replacing parts until the symptom goes away.
If the complaint is that one floor never quite keeps up, rather than the system failing outright, why upstairs is hotter than downstairs sets out what we measure on that kind of call and what usually turns out to be causing it.
Yes, there is a diagnostic fee, as there is with almost every company. It covers a technician driving out and properly testing the system, and it is billed separately from the repair itself. What we will not do is start work before you know the cost. You get the price first, in writing, and you decide.
If you are on our Set It and Forget It maintenance plan, 10% comes off the work.
How quickly we can get to you
If you call in the morning, we will usually reach you the same day, including Seabrook and the Bay Area. The honest exception is a day that is already full. We have a set number of technicians, and a late call on a busy day sometimes becomes first thing tomorrow. We will tell you that on the phone rather than let you wait on a technician who is not coming.
Outside normal hours we still answer, and we will come out for a genuine emergency. Out-of-hours work carries a premium, and we tell you what it is before anyone is dispatched.
What we work on
All makes and models, including equipment we did not install and equipment still under warranty. That covers central split systems, packaged units, heat pumps, ductless mini splits and zoned systems, single-speed and variable-speed alike.
We are an American Standard Customer Care Dealer and we also install Mitsubishi, but servicing a brand and selling a brand are different things. We are not going to tell you a repairable system needs replacing because we happen to sell a different badge.
Repair, or replace?
The honest answer depends on three things: the age of the system, what has actually failed, and how much longer you plan to be in the house. A capacitor on an eight-year-old system is an easy call. A compressor or a leaking evaporator coil on a system approaching fifteen years is a genuine decision, and the arithmetic changes again if the equipment still uses older refrigerant.
We will tell you when a repair is the better spend, and we will tell you when it is not. If it comes to replacement, that is covered on our AC installation and replacement page, and we have written up how to make the repair-or-replace decision in more detail.
Most of what we are called out for was avoidable
Not all of it, but a great deal. The failures that ruin a July weekend were usually visible in March as a weak capacitor, a fouled coil, a low charge or a drain line starting to close up. That is the entire argument for maintenance, and it is why we would rather sell you a spring service than an August compressor.
Our Houston maintenance schedule sets out what to check and when, including the jobs worth doing yourself between visits.
Why people call us
- Family owned and working in southwest Houston for decades
- Licensed under TACLA #00051749C, and insured
- NATE-certified technicians
- All makes and models, including warranty work
- A written quote before any work starts
- 4.9 stars from 200 Google reviews
- We do not buy radio or television advertising, so that cost is not built into your bill
Areas we serve
Castle is based in Fulshear and repairs air conditioners across southwest Houston, Fort Bend County and the Bay Area.
Frequently asked questions
How much does AC repair cost in Houston?
It depends entirely on what has failed. A capacitor and a compressor are not in the same conversation. We charge a diagnostic fee to find out properly, then give you the repair price in writing before any work starts. We have written up what repairs actually cost in Houston and what drives the price.
Do you charge a diagnostic fee?
Yes, like almost every company. It covers a technician driving out and testing the system properly rather than guessing, and it is billed separately from the repair. You are told the repair price before we begin, and you decide.
Can you get here today?
If you call in the morning, usually yes, including Seabrook and the Bay Area. If the day is already full we will say so on the phone rather than leave you waiting. For after-hours emergencies we will travel as far as Galveston, though it takes longer to reach you.
My AC is running but blowing warm air. What is wrong?
Most often low refrigerant, a failing compressor or a dirty outdoor coil. Check the filter and clear any debris from around the outdoor unit first. If the outdoor fan is not turning, switch the system off and call rather than letting it keep running.
Why has my air conditioner stopped by itself?
A very common cause in Houston is the condensate float switch, which cuts power when the drain pan fills so that water cannot reach your ceiling. Check the breaker and thermostat batteries too. If the pan is full, the drain line is the thing to deal with.
Do you work on brands you did not install?
Yes. All makes and models, including warranty work, whoever originally fitted it.
Should I repair or replace my air conditioner?
It depends on the age of the system, what has failed and how long you plan to stay in the house. We will tell you honestly when a repair is the better spend. We would rather keep a working system running than sell you one you did not need.
Do maintenance plan customers get a discount on repairs?
Yes. Customers on our home Set It and Forget It plan get 10% off work we carry out through the year, repairs included.
How Much Does AC Repair Cost in Houston?
What a repair actually costs here, what drives the price, and when repair stops making sense.
Published by Castle Air Conditioning & Heating. Licensed TACLA #00051749C. NATE-certified technicians serving Houston, Fort Bend County and the Bay Area. Quotes in writing before work begins. Last reviewed September 2026.
Air conditioner not cooling? Call or text (713) 667-7606.