While your AC system has many moving parts, only a handful are responsible for most breakdowns we see here in Florida, especially under the constant strain of heat and heavy use.
Knowing which components matter most can help you catch small issues early, avoid costly repairs, and keep your system running efficiently when you need it most.
Let’s break down the four parts of your AC system that cause the majority of problems and what you can do to stay ahead of them.
1. Capacitor – Helps Your AC start and Run Properly
What it is:
A capacitor is a small cylindrical component that stores and releases electrical energy to help your AC’s motors operate properly. Most systems use a run capacitor, and some also have a separate start capacitor for additional starting power.
Where it’s located:
Inside your outdoor unit (the condenser), typically behind a service panel.
What it does:
The run capacitor helps the compressor and fan motors run smoothly and efficiently. In some systems, a separate start capacitor provides an extra boost to help the compressor start.
Why it fails in Florida:
Heat is the biggest enemy. Constant high temperatures and heavy use wear capacitors out faster than in cooler climates.
When it goes bad:
- Your AC won’t start
- You hear a humming noise
- The fan or compressor struggles or won’t turn on
This is not a DIY-friendly repair, capacitors hold electricity even when power is off.
2. Contactor – The “On/Off Switch” for an AC System
What it is:
A contactor is basically a heavy-duty electrical switch that controls when your AC turns on and off.
Where it’s located:
Also inside the outdoor unit, near the capacitor.
What it does:
When your thermostat calls for cooling, it sends a low-voltage signal that pulls the contactor closed, allowing high-voltage power to flow to the compressor and fan.
Why it fails in Florida:
- Moisture causes corrosion inside
- Bugs love getting into them
- The contacts wear out over time
When it goes bad:
- AC won’t turn on
- It won’t turn off
- Clicking or chattering noises
Another part that’s best handled by a professional.
3. Drain Line – The AC “Moisture Exit”
What it is:
A drain line is a pipe (usually PVC or flexible tubing) that carries away the moisture your AC removes from the air.
Where it’s located:
Connected to your indoor unit (air handler), typically running from the evaporator coil to the outside of your home or into a drain.
What it does:
As your AC cools the air, moisture collects on the evaporator coil and drains into a drain pan and out through this line.
Why it fails in Florida:
- High humidity creates constant moisture
- Algae, mold, and sludge build up quickly
- Warm conditions accelerate growth inside the line
When it gets clogged:
- Water leaks around the air handler or ceiling below (if installed in an attic)
- Musty odors develop
- The drain pan fills up
- The system may shut off (many units have a safety switch to prevent overflow)
Homeowners can help prevent clogs by clearing the drain line from the outside using a wet/dry vacuum, which can remove algae and buildup. For deeper cleaning or issues inside the system, professional service is recommended to safely access and clean the drain pan and internal components.
4. Coils & Filters – The AC “Breathing System”
What they are:
- Filters: Catch dust, dirt, and debris from your air
- Coils: Help transfer heat (evaporator coil inside, condenser coil outside)
Where they’re located:
- Filter → inside your home (return vent or air handler)
- Evaporator coil → indoor unit
- Condenser coil → outdoor unit
What they do:
Filters keep airflow clean and unrestricted, while coils allow your system to absorb and release heat efficiently.
Why they fail in Florida:
- Constant AC use = faster buildup
- Outdoor debris (leaves, dirt, pollen)
- Skipped or delayed maintenance
When they’re dirty:
- Weak airflow
- Higher energy bills
- System overheating or freezing up
A clogged filter restricts airflow, which can cause the evaporator coil to get too cold and ice over. This is one of the most common AC issues in Florida.
This is the easiest problem to prevent:
- Change filters regularly (every 1–3 months)
- Keep outdoor unit clean
- Schedule routine maintenance
Most AC breakdowns we see come back to these four things.
Some, like filters and drain lines, you can stay ahead of with regular attention. Others, like capacitors and contactors, require proper tools and experience to diagnose safely. That’s why AC companies in Tampa Bay exist!
Staying proactive can save you from a full system breakdown in the middle of a Florida summer.
Need help keeping your AC running right?
Poulin Cooling is here when you need us, whether it’s maintenance, repairs, or just a quick check-up to catch problems early. Call us at (727) 252-9602 or reach out to us online.
Check out this quick video for more information about the top four parts that cause your AC to break down: YouTube Video Link: https://www.youtube.com/shorts/oHclBOWU0AM