Central AC Stopped Working? Here's What Every McKinney Homeowner Should Do First

When the heat index climbs past 100 in McKinney and your central AC stops working, the house warms up fast. Before you pay for a service call, there are a few quick checks worth doing. Many "AC not working" calls turn out to be simple fixes a homeowner can handle in minutes — if you know what to check and in what order.

We've built this guide from years of running calls across McKinney and North Collin County. The first three steps are free and take under five minutes. The next three rule out common mid-level issues. The last step tells you when to stop and call a licensed pro.

Work through them in order. You may get your system running again before we even pick up the phone.

When your central AC stops working, do these seven checks in order:

1. Check the thermostat — batteries, setting, and mode.
2. Reset the circuit breakers for the AC and air handler.
3. Replace the air filter if it looks dirty.
4. Clear the outdoor unit of leaves, grass, and debris.
5. Check for ice on the indoor coil or refrigerant lines.
6. Look at the condensate drain pan — a full pan trips a safety switch.
7. If none of these work, stop troubleshooting and call a licensed HVAC technician.

Start with step one and move down the list. Most fixes happen in the first three checks.

Before anything else, walk up to the thermostat. A surprising number of AC problems start and end here. This check costs nothing and takes less than a minute.

Go through these quick items:

• Mode setting: Confirm it's set to "Cool" — not "Fan," "Off," or "Heat."
• Target temperature: Make sure it's set below the current room temp.
• Display: If the screen is blank or dim, replace the batteries.
• Schedule overrides: Check that no one bumped the system into a hold or vacation mode.

If you have a smart thermostat, open the app and check the Wi-Fi connection. Many newer McKinney homes run on Nest, Ecobee, or Honeywell units, and a dropped Wi-Fi signal can stop the system from running as expected. A quick restart of the thermostat or the home router often brings it back.

If the thermostat checks out, move to the breakers next.

If the thermostat looks fine, the next free check is your electrical panel. A tripped breaker is one of the most common reasons a central AC stops working.

Find your main panel and look for breakers labeled for the AC, condenser, or air handler. A tripped breaker sits between "on" and "off," or looks slightly out of line with the others. To reset it, flip it fully to "off" first, then back to "on." Never just nudge it.

Many newer McKinney homes built in master-planned communities have a sub-panel in the garage or utility room. Check both the main panel and any sub-panels. There's also an outdoor disconnect box next to the condenser — open it and confirm the switch or pull-out is engaged.

Here's the part that matters most:

• If the breaker holds after a reset, you're back in business.
• If it trips again right away, stop. Do not keep resetting it.

A breaker that keeps tripping is protecting your home. Something is pulling too much power, and that needs a licensed electrician — not another reset. Our team handles plumbing, HVAC, and electrical under one roof, so one call covers it. See our electrical service in McKinney if you need that side of the problem checked.

If the breakers are fine, the next check is the air filter.

A clogged air filter can make a healthy AC act broken. When the filter chokes off airflow, the evaporator coil gets too cold and freezes over. Once that happens, the system stops cooling — even though nothing is actually wrong with the AC itself.

Find your filter in one of two places:

• Return grille on a wall or ceiling (the large vent with the filter behind it)
• Air handler near the indoor unit — often in an attic, closet, or garage

Many newer McKinney homes use a large media filter at the air handler. These are thicker than a standard one-inch filter and sit in a dedicated housing. Check the side of the filter for the size printed on the frame.

Hold the filter up to a light. If you can't see light through it, replace it. How often you change it depends on your home, but North Texas throws a lot at a filter — pollen, construction dust from growing areas around McKinney, and pet dander all build up fast. Most homes need a new filter every 1 to 3 months during heavy cooling season.

One warning: never run the system with no filter at all. Dust and debris will coat the coil and create a bigger repair down the road. If you're between sizes or schedules, schedule an AC tune-up and we'll set you up with the right filter for your unit.

With a clean filter installed, head outside to the condenser next.

Your outdoor unit — the condenser — needs room to breathe. When leaves, grass, or mulch crowd the fins, hot air can't escape and the system loses its ability to cool. This is a common cause of a central AC that seems to run but won't cool the house.

Before you touch anything, shut off power at the outdoor disconnect. It's the metal box mounted on the wall next to the condenser. Safety comes first — always.

Then walk around the unit and clear what you find:

• Grass clippings and leaves built up against the fins
• Cottonwood fluff or pollen mats across the coil
• Pet hair or dirt tracked in by lawn equipment
• Mulch or landscaping bark pushed too close to the base

Many McKinney homes sit in HOA communities with dense landscaping. Mulch beds, shrubs, and tree preservation areas can crowd a condenser over a single growing season. Keep at least 2 feet of clear space on all sides.

Once the area is clear, take a garden hose and rinse the coil gently from the inside out, using low pressure. This pushes debris back the way it came instead of deeper into the fins. Never use a pressure washer. And don't bend or press on the aluminum fins — once crushed, they block airflow and can only be combed out by a technician.

Restore power, wait a few minutes, then start the system and see if it cools.

Still not cooling? We offer 24/7 emergency AC service in McKinney for homeowners who can't wait through the heat.

If the outdoor unit is clear and the system still isn't working, there's one more thing that can mimic a broken AC: ice.

Ice on an AC system sounds backwards, but it happens more than you'd think. When you see it, stop running the system. Continuing to run a frozen AC can damage the compressor — the most expensive part of the unit.

Check two spots:

• Indoor evaporator coil — near the air handler, often behind an access panel
• Outdoor refrigerant line — the larger, insulated copper line running from the house to the condenser

If you see frost, ice, or a sweating buildup, the system has frozen over. This points to one of three causes: low refrigerant, restricted airflow, or a failed blower motor.

Here's what to do right now:

• Turn the AC off at the thermostat
• Switch the fan setting to "On" (not "Auto") to move warm air across the coil
• Let it thaw for 1 to 3 hours — longer if the ice is thick
• Do not chip, scrape, hammer, or try to melt the ice with heat

Use this quick reference to see where the ice points:

Once the system is fully thawed, turn it back on and see if it cools. If ice returns within a few hours, stop running the system and call us. Refrigerant work is not a DIY job — federal rules require EPA-certified technicians to handle it.

If the coils are clear and dry, there's one more hidden shutoff to check.

Your AC pulls humidity out of the air as it cools. That moisture collects in a drain pan under the indoor unit and exits through a PVC pipe — the condensate drain line. When that line clogs, the pan fills up and a small safety switch shuts the whole system down.

This is one of the most overlooked reasons a central AC stops working. Many McKinney homeowners never think to check it.

Find the drain line at the indoor unit. One end sits under the evaporator coil; the other exits outside near the condenser or drains into a utility sink. North Texas summers run humid, which means drain lines work hard and clog faster.

Signs the drain is your problem:

• Water pooling under the indoor unit or in the drain pan
• A wet spot on the ceiling below an attic air handler
• The system starts, runs briefly, then shuts itself off
• Nothing seems wrong at the thermostat or breakers

For a safe DIY check, look at the pan first. If you see standing water, the line is likely clogged. You can empty the pan with towels or a wet/dry shop vac. Some homeowners can clear a minor clog by running the shop vac at the outdoor end of the drain line for a minute or two.

If the pan keeps filling, or you can't reach the line, stop there. A clogged drain often means algae or sludge inside the pipe, and it needs to be flushed properly. We handle AC condensate drain cleaning as part of our regular service calls.

If the drain is clear, one more outdoor check can still save you a service call.

The last free check is a quick walk around the outside of your home. Storms, yard work, and pets can all flip switches or trip outlets that cut power to your AC. Many homeowners never know these exist.

Start with the outdoor disconnect. This is the metal box mounted on the exterior wall next to your condenser. Open the cover and look inside. You'll see one of two setups:

• A switch that should be in the "on" position
• A pull-out fuse block that should be fully seated in the slot

If the switch is off or the fuse block is loose, set it back in place and check the system. Some older homes in the area still use pull-out fuses with actual cartridge fuses inside. If one of those is blown, the AC won't start — and that's a job for a pro.

Next, check any GFCI outlets near the condenser or in the garage. North Texas spring and early summer bring heavy storms across North Collin County, and a power surge can trip these outlets. Press the "reset" button and see if the system powers back up.

One rule here: reset each switch or outlet once. If it pops right back, stop. Repeated tripping signals a wiring issue or a failing component. Both need a licensed technician, not another reset.

If everything outside looks right and the AC still won't run, you've done your part. It's time to call in help.