Few things are worse in an Austin summer than walking past a vent and feeling warm air. The good news: the cause is often simple. Here are the seven problems our technicians see most, starting with the ones you can check yourself.
1. The thermostat is set wrong
Check that the mode is set to Cool, not Heat or Off, and that the fan is on Auto. When the fan is set to On, it keeps blowing between cooling cycles, which can feel like warm air. Replace thermostat batteries if the display is dim or blank.
2. The air filter is clogged
A dirty filter chokes airflow across the indoor coil. Over time the coil can ice over, and cooling drops off sharply. In Austin, with systems running most of the day, many homes need a new filter every month in summer.
3. The outdoor unit lost power
If the indoor fan runs but the outdoor unit is silent, check your breaker panel for a tripped breaker labeled AC or condenser. Reset it once. If it trips again, leave it off and call a technician, since repeat trips point to an electrical fault.
4. A failed capacitor
The capacitor gives the compressor and outdoor fan motor the jolt they need to start. Summer heat wears them out, and they are one of the most common repairs we make. A humming outdoor unit with a fan that does not spin is a classic sign. Capacitors hold a dangerous charge, so this is a job for a professional.
5. Low refrigerant from a leak
Refrigerant is not used up like fuel. If it is low, there is a leak. Signs include ice on the copper lines, a hissing sound and a system that runs constantly without cooling. Handling refrigerant requires EPA certification, and the leak needs to be found and repaired, not just topped off.
6. A dirty outdoor coil
The outdoor coil releases heat from your home. When it is packed with dust, grass clippings or cottonwood fluff, it cannot do that job well. Keep about two feet clear around the unit. A technician can clean the coil safely during a tune-up.
7. A clogged condensate drain
Your AC removes moisture from the air, and that water drains away through a small line. When the line clogs, a safety switch can shut down cooling to prevent water damage. Water around the indoor unit or a full drain pan are the tell-tale signs.
Safe checks before you call
- Thermostat set to Cool, fan on Auto, batteries fresh
- Air filter clean or replaced
- Breaker for the outdoor unit on
- Outdoor unit clear of leaves, grass and debris
When to call a technician
If the basic checks do not fix it, or you notice ice, buzzing, burning smells or water leaks, turn the system off and call. Running an AC with a refrigerant or electrical problem can turn a small repair into a compressor replacement.
The bottom line
Most warm-air problems come down to airflow, power or a worn part. A quick check of the thermostat, filter and breaker solves some of them. For everything else, a diagnosis takes the guesswork out, and you will know the cost before any work begins.