What to Check Before Calling an AC Repair Company
March 29, 2026 By: One Way Heating & Cooling
Is there anything more frustrating than your air conditioner quitting on the hottest day of the year? We’ve all been there. You feel that puff of warm air, or worse—total silence—and your first instinct is to reach for the phone.
But before you schedule a service call, take a deep breath. At One Way Heating and Cooling, we want to help you save time and money. Often, the "breakdown" is actually a simple setting or a minor maintenance issue you can fix in five minutes.
In this guide, we’ll walk you through a comprehensive DIY checklist. If these steps don’t get the cold air flowing, then you’ll know for sure it’s time to call in the pros.
Is your thermostat set correctly?
It sounds simple, but you would be surprised how often a thermostat is the culprit. Sometimes a family member changes the settings, or a power flicker resets the programming.
First, ensure the thermostat is set to "Cool." If it’s on "Heat" or "Fan Only," the compressor won't kick in. Next, check the temperature setting. It needs to be at least 3 to 5 degrees below the current room temperature to trigger a cooling cycle.
If you have a programmable thermostat, check the "Hold" or "Schedule" settings. An accidental "Permanent Hold" at a high temperature can make it feel like the system isn't working when it's actually just following orders.
Do the thermostat batteries need replacing?
If your thermostat screen is blank or fading, the batteries are likely dead. Many homeowners don't realize that even hardwired systems often have battery backups that can cause communication errors when they get low.
Most thermostats take AA or AAA alkaline batteries. Pop the cover off, swap in fresh ones, and see if the display returns. If the screen is back but the AC still won't start, wait a few minutes—most systems have a built-in delay to protect the compressor from short-cycling.
Has a circuit breaker tripped?
Your air conditioner pulls a lot of power, especially during a heatwave. This can sometimes cause the circuit breaker to trip.
Head to your home’s electrical panel (usually in the garage, basement, or a utility closet). Look for the switches labeled "AC" or "HVAC." If the switch is in the middle position or flipped to "Off," flip it all the way to "Off" first, then back to "On."
Note: If the breaker trips again immediately or frequently, do not keep resetting it. This indicates a serious electrical issue or a failing component, and you should call One Way Heating and Cooling right away to prevent a fire hazard.
When was the last time you changed your air filter?
A dirty air filter is the number one cause of AC service calls. When the filter is clogged with dust, pet hair, and dander, the system can’t "breathe."
This lack of airflow causes two major problems:
The unit works harder: This leads to higher energy bills and parts wearing out faster.
The coils freeze: Without enough warm air passing over the evaporator coils, they get too cold and turn into a block of ice.
If you see ice on the copper lines or the indoor unit, turn the AC off, switch the fan to "On" to help it thaw, and replace the filter immediately. We recommend changing standard filters every 30 to 90 days.
Are your air vents and registers open?
Check every room in your house. Are the supply vents open? Are they blocked by furniture, rugs, or heavy curtains?
Closing vents in unused rooms is a common mistake. Homeowners often think they are saving money, but HVAC systems are designed for specific airflow volumes. Closing too many vents increases "static pressure," which can damage your blower motor and cause the system to shut down. Keep at least 80% of your vents open at all times.
Is the outdoor unit clear of debris?
Your outdoor condenser unit needs space to release the heat it pulled from inside your home. If it’s crowded by tall grass, weeds, or fallen leaves, it will overheat.
Take a walk outside and check the following:
Clearance: Ensure there is at least 2 feet of clear space around the unit and 5 feet above it.
Cleanliness: If the metal fins look caked with dirt or "cottonwood" fuzz, you can gently spray them with a garden hose (do not use a pressure washer, as it will bend the delicate fins).
Power Switch: Check the "disconnect" box near the outdoor unit. Ensure the handle or switch is in the "On" position.
Is the condensate drain line clogged?
Your AC doesn't just cool the air; it removes humidity. That moisture drips into a pan and travels through a PVC pipe called a drain line. Over time, algae and mold can grow inside this pipe, causing a clog.
Most modern systems have a "float switch" safety device. If the water backs up, the switch flips and kills power to the unit to prevent your house from flooding.
Check the drain pan under your indoor unit. If you see standing water, you likely have a clog. You can sometimes clear these using a wet/dry vacuum to suck the debris out from the exterior end of the pipe.
What should you do if the AC is making strange noises?
If you hear banging, screeching, or grinding, stop your troubleshooting and turn the system off immediately.
Banging: Usually indicates a loose part in the compressor.
Screeching: Often a failing belt or a bad motor bearing.
Buzzing: Usually an electrical issue, like a failing capacitor or contactor.
Running a system that is making loud mechanical noises can turn a simple repair into a total system replacement. This is the point where DIY ends and professional expertise begins.
Why choose One Way Heating and Cooling?
When the DIY checks aren't enough, you need a team you can trust. One Way Heating and Cooling has been serving the community with integrity for decades. Our technicians are NATE-certified and factory-trained to work on all makes and models.
We pride ourselves on:
Fast Response Times: We know that a broken AC is an emergency in the summer.
Upfront Pricing: No hidden fees. We explain the repair before we start.
Family-Owned Values: We treat your home like our own.
Don't suffer in the heat! If you've checked your filters and breakers and still can't get cool, contact One Way Heating and Cooling today to schedule your expert diagnostic visit.
Frequently Asked Questions (FAQ)
Q: How often should I realistically change my air filter?
A: For a standard 1-inch filter, you should check it once a month. If you have pets or allergies, you’ll likely need to change it every 30 days. In a home with no pets and high-quality pleated filters, you might get away with every 90 days.
Q: My AC is running, but only warm air is coming out. What’s wrong?
A: This usually points to a refrigerant leak, a failed compressor, or a very dirty outdoor unit. If you’ve already checked your thermostat and filter, this requires a professional technician to gauge the pressure levels and check for leaks.
Q: Is it okay to spray my outdoor unit with a hose?
A: Yes! Keeping the coils clean is vital for efficiency. Use a gentle stream of water. Avoid high-pressure settings, as they can flatten the aluminum fins and permanently restrict airflow.
Q: Why does my AC keep tripping the circuit breaker?
A: A breaker trips when the system draws too much electricity. This can be caused by a failing motor, a "grounded" compressor, or even a loose electrical wire. It is a safety feature designed to prevent a fire, so if it happens more than once, call a professional.
Q: Can I ignore a small water leak near my furnace?
A: No. Even a small leak can lead to mold growth and structural damage to your floors. It usually indicates a clogged drain line or a cracked drain pan, both of which should be addressed immediately.