Why Is My AC Constantly Running?
An AC that runs constantly without reaching the set temperature is usually caused by a dirty air filter, low refrigerant, an undersized system, air leaks in the home, or a thermostat set too low for the conditions. On the hottest Pittsburgh days (95F+), some systems run continuously and that can be normal. But if it runs non-stop on moderate days, something is wrong.
THE DETAILS
Check the filter first. A dirty filter restricts airflow and makes the system work harder and longer to cool.
Low refrigerant reduces cooling capacity, so the system runs constantly trying to reach the set temperature but never does.
An undersized AC cannot keep up with the cooling load. This is common in homes that have had additions built on or where the original system was sized for a smaller space.
Air leaks around windows, doors, and in the attic let hot air in faster than your AC can cool it. Sealing these leaks can dramatically reduce run time.
The thermostat may be set too low. Setting it to 68F when it is 95F outside is asking a lot. Try 74-76F and see if the system can maintain that.
🔧 WHEN TO CALL A PRO
If your AC runs constantly on days that are not extremely hot, and the filter is clean, call a pro to check refrigerant levels and system sizing.