AC Running Constantly

If the system is undersized for the space (or the heat load is extreme), the AC can't keep up. It runs continuously trying to reach setpoint but never quite gets there. Normal during 95°F+ days even for properly-sized systems.

Outdoor temp 90°F+ and system can't catch up = often just extreme load. If happens on 80°F days too = undersized.

Less refrigerant = less heat absorbed per cycle = system runs longer to remove the same heat. As leak gets worse, runtime increases until system can't reach setpoint at all.

Weak temperature drop across the indoor coil (less than 15°F), ice on the suction line, longer run times that have grown worse over weeks or months.

Clogged outdoor coils can't reject heat efficiently. System runs continuously trying to compensate. Often the cause when symptoms start gradually over a single cooling season.

Visual inspection — fins matted with cottonwood, dust, grass clippings.

If fan is set to ON instead of AUTO, the blower runs continuously — regardless of cooling state. You hear constant airflow but the system isn't actively cooling all the time. Easy to mistake for AC running constantly.

Check the FAN setting on your thermostat. Should be AUTO for normal operation.

Cooled air escapes into attic, crawlspace, or wall cavities instead of reaching living spaces. System runs longer trying to deliver effective cooling. Can lose 20-40% of capacity to leaks.

Inspect accessible ductwork for disconnected sections, holes, or gaps at joints. Feel for cool air leaking from duct seams in unconditioned spaces.

Thermostat fails to read indoor temperature correctly, never satisfies its cooling call. Or stuck contactor at the outdoor unit keeps the compressor running regardless of thermostat command.

Compare thermostat reading to a separate thermometer. Difference of 5°F+ suggests thermostat failure. Stuck contactor: AC keeps running even when you turn thermostat fully OFF (only the disconnect stops it).