AC Repair Glossary

The thermostat is the control interface that allows you to set and regulate the temperature in your home. It signals the AC system to turn on or off based on the indoor temperature reading. A malfunctioning thermostat — whether due to dead batteries, faulty wiring, or sensor issues — can cause the system to short-cycle, run continuously, or fail to respond entirely, mimicking symptoms of a more serious mechanical failure.

Short cycling is an AC malfunction where the system turns on and off in rapid, repeated intervals without completing a full cooling cycle. This behavior puts excessive strain on the compressor, increases energy consumption, and prevents your home from reaching the desired temperature. Short cycling can be caused by an oversized unit, refrigerant leaks, a dirty air filter, or a failing thermostat, and should be diagnosed promptly to avoid compressor damage.

SEER stands for Seasonal Energy Efficiency Ratio and measures how efficiently an air conditioning system converts electricity into cooling output over an entire season. A higher SEER rating indicates greater energy efficiency and lower operating costs. When replacing or repairing an AC unit, understanding SEER ratings helps homeowners evaluate long-term savings versus upfront investment and ensures compliance with current efficiency standards.

A capacitor is an electrical component that stores and releases energy to start and run the motors in your AC system, including the compressor and fan motors. There are two types: start capacitors and run capacitors. A failing capacitor is one of the most common and affordable AC repairs — symptoms include a humming sound from the outdoor unit, the fan spinning slowly or not at all, or the system failing to start despite the thermostat signaling it to run.