In this article…
- Step 1: Identify What Your AC Is (or Isn’t) Doing
- Step 2: Try These Simple AC Troubleshooting Steps
- Step 3: See If the Simple Fix Solved the Problem
- Step 4: Know When to Call an HVAC Professional
- Step 5: Understand What Type of AC Repair You May Need
- Having Realistic Expectations For Your AC Repair
When your AC stops working properly, you may immediately assume the worst. But a warm house doesn’t always mean you need a major AC repair.
Sometimes, the problem can be as simple as a faulty thermostat setting, dirty air filter, or tripped breaker. Other times, there may be an electrical, airflow, or mechanical problem that requires an HVAC professional to properly diagnose.
While you probably won’t be able to determine exactly which component has failed without a professional diagnosis, there are a few things you can do to better understand what’s happening.
At Wright Home Services, we’ve been helping San Antonio homeowners maintain their comfort and peace of mind since 1979.
If you ever have AC problems, our goal is to be your go-to source with accurate information and tips and tricks for troubleshooting our most frequently asked HVAC questions.
So, whether you’re experiencing an AC issue right now or just want to know what to do, we’re here to help.
Here’s a simple step-by-step process to help you troubleshoot an AC problem, rule out some of the easier fixes, and determine when it’s time to call an HVAC professional.
Step 1: Identify What Your AC Is (or Isn’t) Doing
Before you start troubleshooting, take a minute to identify exactly what seems different about your AC.
Instead of trying to determine which part is broken, focus on what you can see, hear, and feel.
Ask yourself:
- Is the AC turning on at all?
- Is the system running but not blowing air?
- Is air coming from the vents but it isn’t cold?
- Is the AC running constantly not reaching the thermostat setting?
- Is the thermostat blank or not responding?
- Is the system turning on and off more frequently than normal?
- Is the outdoor AC unit running?
- Are some rooms significantly warmer than others?
- Is there ice on the AC unit or refrigerant lines?
- Is there water around the indoor unit?
- Is the system making a new or unusual noise?
- Do you notice any unusual or burning smells?
Your observations won’t necessarily tell you exactly what’s wrong, but they can help narrow down the possibilities.
For example, an AC that’s running but blowing warm air could have an airflow problem, refrigerant issue, dirty coil, electrical problem, or another malfunction. That’s why it’s important not to jump to conclusions based on one symptom.
You don’t necessarily need to know why your AC isn’t cooling yet. Start by figuring out exactly what it is doing differently.
Step 2: Try These Simple AC Troubleshooting Steps
Once you’ve identified the symptoms, there are a few basic things you can safely check before scheduling an AC repair.
1. Check Your Thermostat
Start with the thermostat.
Make sure the thermostat is set to COOL, and the temperature is set several degrees below the current temperature inside your home.
You should also check the fan setting. If the fan is set to ON, the blower may continue circulating air even when the AC isn’t actively cooling. This can sometimes make it seem like the AC is blowing warm air.
If your thermostat uses batteries, replace them if the screen is blank or the thermostat isn’t responding.
2. Check Your Air Filter
Next, take a look at your air filter.
A dirty filter restricts the amount of air that can move through your system. In more severe cases, restricted airflow can affect cooling performance and may even contribute to the evaporator coil freezing.
If your filter is visibly dirty or hasn’t been replaced recently, change it and see if airflow improves.
3. Make Sure Your Vents Aren’t Blocked
Walk around your home and check your supply and return vents.
Make sure they aren’t closed or blocked by furniture, rugs, plants, curtains, boxes, or other household items.
If the problem is isolated to one particular room, also pay attention to whether that room has noticeably less airflow than the rest of the house. That could point toward an airflow or ductwork problem rather than a problem with the AC equipment itself.
4. Check Your Breaker
If your AC isn’t turning on, check your home’s electrical panel to see whether the breaker controlling your HVAC equipment has tripped.
You can reset a tripped breaker once. However, if it trips again, don’t continue resetting it.
A breaker that repeatedly trips can indicate an electrical or equipment problem that needs to be professionally diagnosed.
5. Look at the Outdoor AC Unit
If your thermostat is calling for cooling, take a look at your outdoor condenser.
Is it running? Can you hear the compressor or see the condenser fan spinning?
If your indoor blower is running but the outdoor unit isn’t, that is useful information to give your HVAC technician. Problems with capacitors, contactors, motors, electrical components, and other parts of the system can prevent the outdoor unit from operating properly.
6. Look for Ice or Water
Check the visible refrigerant lines and the area around your indoor HVAC equipment.
Ice can be a sign of restricted airflow, a dirty evaporator coil, blower problems, low refrigerant, or another issue. Water around the indoor unit could point toward a clogged condensate drain, drainage problem, or ice that has begun to melt.
If your AC is frozen, don’t continue running it in cooling mode. The ice will need to completely thaw before the underlying problem can be properly diagnosed.
7. Listen and Smell
You know what your HVAC system normally sounds like. If you suddenly hear buzzing, grinding, banging, squealing, hissing, or another unfamiliar sound, make a note of it.
The same applies to unusual smells.
A slight smell when you first turn on the heat for the season can be normal, but a strong burning or electrical smell coming from your HVAC equipment should not be ignored.
Step 3: See If the Simple Fix Solved the Problem
Sometimes, basic troubleshooting really does solve the problem.
Maybe someone accidentally changed the thermostat setting. Maybe the air filter was extremely dirty. Or maybe a piece of furniture was blocking an important return vent.
After correcting anything obvious, give your AC some time to operate and pay attention to how it responds.
Ask yourself:
- Is cold air coming from the vents again?
- Has airflow returned to normal?
- Is the indoor temperature beginning to drop?
- Is the AC cycling normally?
- Has the unusual behavior stopped?
If everything returns to normal, continue monitoring the system.
However, don’t ignore a problem that keeps coming back.
For example, if your AC freezes, you allow it to thaw, and then it freezes again, there’s likely an underlying problem that still needs to be addressed. The same is true for a breaker that repeatedly trips or an AC that temporarily starts working again before experiencing the same problem.
Step 4: Know When to Call an HVAC Professional
There is a difference between troubleshooting an AC problem and actually diagnosing one.
Troubleshooting allows you to rule out simple causes and gather information about what’s happening. A professional AC diagnostic involves testing the system to determine exactly what’s causing the problem.
It’s generally time to call an HVAC professional if:
- Your AC still isn’t cooling after basic troubleshooting
- The system won’t turn on
- The breaker repeatedly trips
- The indoor blower runs but the outdoor AC unit doesn’t
- Your AC repeatedly freezes
- There’s water leaking around your HVAC equipment
- Airflow is extremely weak
- The system repeatedly turns on and off
- You hear grinding, buzzing, banging, or other unusual noises
- You notice a strong burning or electrical smell
- The same AC problem keeps coming back
At this point, determining what’s wrong may require checking electrical components, motors, refrigerant pressures, temperature differences, airflow, and other parts of the HVAC system.
There are also certain things homeowners should leave to a professional.
Don’t open electrical compartments, test or replace capacitors, handle refrigerant, bypass safety switches, or begin taking apart HVAC equipment unless you’re properly trained to do so.
HVAC systems contain high-voltage electrical components and pressurized refrigerant that can make DIY repairs dangerous.
Step 5: Understand What Type of AC Repair You May Need
Even after you’ve gone through these troubleshooting steps, you probably won’t know the exact repair your AC needs, and that’s okay.
What you may be able to determine is the general type of problem you’re experiencing.
For example:
Airflow Problems
If you’re experiencing weak airflow, uneven temperatures, freezing, or an AC that struggles to cool the house, the problem could be related to airflow.
Possible causes can include:
- Dirty air filters
- Blower problems
- Dirty evaporator coils
- Damaged or disconnected ductwork
- Duct leaks
- Other airflow restrictions
Some airflow problems are relatively simple to correct, while others require repairs to the blower or duct system.
Electrical Problems
If your AC won’t start, the outdoor unit isn’t running, the breaker keeps tripping, or you hear buzzing from the equipment, you may be dealing with an electrical problem.
Possible repairs could involve:
- Capacitors
- Contactors
- Thermostats
- Wiring
- Motors
- Other electrical components
Because HVAC equipment uses high-voltage electricity, electrical repairs should be handled by a high-quality, certified professional.
Cooling or Refrigerant Problems
If your AC is running and has normal airflow but the air isn’t getting cold, the problem may be somewhere within the cooling process itself.
Potential causes can include:
- Dirty evaporator or condenser coils
- Refrigerant leaks
- Improper refrigerant charge
- Metering device problems
- Compressor problems
One important thing to remember is that refrigerant isn’t something your AC normally “uses up.” If the system is significantly low on refrigerant, a technician may need to determine why rather than simply adding more.
Drainage Problems
Your AC removes moisture from the air as it cools your home, and that moisture needs somewhere to go.
Water around your indoor HVAC equipment can be caused by:
- A clogged condensate drain
- A damaged drain pan
- A condensate pump problem
- A frozen evaporator coil that is thawing
Drainage problems may seem minor, but they shouldn’t be ignored. Water in the wrong place can potentially damage HVAC equipment or areas of your home surrounding the system.
Major Component Problems
In some cases, troubleshooting may ultimately lead to a larger mechanical repair.
Major components within your AC system include the:
- Compressor
- Blower motor
- Condenser fan motor
- Evaporator coil
- Condenser coil
A problem involving one of these components doesn’t automatically mean you need to replace your entire HVAC system.
The age and condition of the equipment, cost of the repair, warranty coverage, and overall performance of the system should all be considered before making that decision.
Having Realistic Expectations For Your AC Repair
Now you have a step-by-step guide on what to do when you experience an AC issue, can easily troubleshoot simple issues, and understand when to call a professional.
Start with what you can observe. Identify what the system is or isn’t doing, check the thermostat and filter, look for obvious airflow or electrical issues, and see whether a simple fix solves the problem.
If it doesn’t, that’s when it’s time to bring in an HVAC professional.
A proper AC diagnostic can determine whether you’re dealing with a relatively minor repair, such as a capacitor or clogged drain, or a more significant problem involving a motor, coil, compressor, or another major component.
Either way, the more you understand about what’s happening with your system, the better prepared you’ll be to ask questions, understand your repair options, and make an informed decision about what comes next.
And if your system is over 12 years old, the truth is it may be worth considering a full system replacement. So, if you have been experiencing constant issues with your older HVAC system, you may have been wondering if a full system replacement is worth it for you.
Check out this article that outlines 15 questions to think about when it comes to repairing or replacing your system, like the type of issue you’ve been experiencing, how long you plan to live in your home, what you’d like to improve when it comes to your comfort, and more.
