By Hood Service Company · Corsicana, TX · Updated
The short version
- An air conditioner moves heat from inside to outside; it doesn't create cold air.
- Refrigerant circulates in a sealed loop, so a low charge almost always means a leak.
- Airflow matters as much as refrigerant, and a clogged filter can stop a healthy system from cooling.
- Removing humidity is part of the job, which is why correct sizing matters.
What does a central air conditioner actually do?
It pulls heat and moisture out of your indoor air and releases the heat outdoors. The cool air you feel is your own air with heat removed, sent back through the ducts.
Most homes in North-Central Texas have a split system: an outdoor unit holding the compressor and outdoor coil, and an indoor furnace or air handler holding the indoor coil and blower. A packaged unit puts every part in one cabinet.
How does refrigerant move heat out of the house?
Refrigerant absorbs heat as it evaporates in the indoor coil and gives it up as it condenses in the outdoor coil. The compressor keeps it moving, and a metering device controls the pressure drop.
The loop is sealed. Refrigerant isn't used up like fuel, so a system that's low on charge has a leak somewhere. Adding refrigerant without fixing the leak only delays the next breakdown.
- Indoor coil: cold, low-pressure refrigerant absorbs heat from the air the blower pushes across the evaporator coil.
- Compressor: in the outdoor unit, it squeezes the refrigerant vapor, raising its pressure and temperature.
- Outdoor coil: the outdoor fan pulls air across the hot coil, and the refrigerant releases its heat and turns back into a liquid.
- Expansion valve or metering device: drops the pressure so the refrigerant is cold again before it returns to the indoor coil.
Why does an air conditioner remove humidity?
When warm, humid air crosses the cold indoor coil, moisture condenses on it like water on a cold glass. That water drains away through the condensate line, leaving drier air behind.
Drier air feels cooler at the same temperature, which matters during the humid stretch of a Texas spring and early summer. An oversized system can cool the house quickly and shut off before it has removed much moisture, leaving rooms cool but clammy. That's one reason sizing should start with a load calculation, not a guess.
What usually goes wrong with central air?
Most problems fall into a few groups: restricted airflow, refrigerant leaks, worn start-up parts and drainage. Each one usually shows up as weaker cooling before the system stops completely.
If your system is acting up now, the HVAC troubleshooter walks through the safe checks one symptom at a time.
- Airflow: a dirty filter, closed vents or a dirty coil starves the indoor coil of warm air, and it can freeze. See why an evaporator coil freezes.
- Refrigerant: a leak lowers the charge, so the system runs longer and cools less.
- Start-up parts: a failing capacitor or contactor can keep the outdoor unit from starting even while the indoor fan runs.
- Drainage: a clogged condensate line can back water up or trip a safety switch that shuts cooling off.
Which refrigerant does your system use, and does it matter?
It matters for service. R-22 production and import ended January 1, 2020, so older R-22 systems rely on existing and reclaimed supply. New residential systems are moving to lower-GWP refrigerants such as R-454B and R-32.
The refrigerant type is printed on the outdoor unit's data label. Refrigerants aren't interchangeable, and adding or recovering them is work for a trained technician from a licensed HVAC contractor, never a DIY job. If you're weighing a repair on an older R-22 system, our guide to repairing or replacing your HVAC covers the trade-offs.
How do you keep a central AC running well?
Change the filter on schedule, keep the outdoor unit clear, and have the system checked each spring before the heat arrives. A tune-up catches weak parts and slow leaks while they're still small.
Keep the outdoor unit clear of grass and leaves. Beyond that, an AC tune-up typically checks charge, airflow, drainage and the parts that wear. Hood Comfort Club members get a spring and a fall tune-up every year; see our maintenance plans. For everything else, start with our air conditioning services.
When should you call a technician?
- The outdoor unit hums or clicks, but the fan and compressor won't start.
- Ice on the refrigerant lines or indoor coil comes back after you thaw it and change the filter.
- The system runs constantly, but the air from the vents is barely cooler than the room.
- Water pools around the indoor unit, or a breaker trips again after one reset.
Frequently asked questions
Is it normal for water to drip outside near my AC?
Yes, water from the condensate line draining outside is normal in cooling season. It's the moisture the system removed from your indoor air. Water pooling indoors around the furnace or air handler is not normal and usually points to a clogged drain or a coil that froze and is thawing.
Should the large line to the outdoor unit feel cool?
When the system is cooling, the larger insulated line usually feels cool and may sweat a little. Frost or ice on it is a warning sign, often of low airflow or low refrigerant charge. If ice keeps forming, turn cooling off and have it checked.
How long does a central air conditioner last?
It depends on maintenance and use. Many systems last roughly 10 to 15 years, but a neglected system can fail sooner. Regular filter changes and yearly tune-ups help yours last.