Why Is My AC Not Cooling?
Your AC is not cooling because of a dirty air filter (most common), low refrigerant, a frozen evaporator coil, thermostat issues, a dirty condenser unit, or undersized ductwork. Check your filter and thermostat first. If those are fine, clean the outdoor unit. If the problem continues, you likely need a professional to check refrigerant levels or diagnose a mechanical issue.
THE DETAILS
A dirty air filter is the single most common reason an AC stops cooling properly. It restricts airflow to the evaporator coil, which can cause the coil to freeze. Replace the filter and give the system a few hours to recover.
Low refrigerant means the system cannot absorb enough heat from your indoor air. Your AC runs constantly but never reaches the set temperature. This is caused by a leak — not normal usage — and needs professional repair.
A dirty outdoor condenser cannot release heat efficiently. Clear debris, hose it down gently, and maintain 2 feet of clearance on all sides.
In many older Pittsburgh homes, the ductwork is undersized or leaky. You could be losing 20-30% of cooled air into walls, attics, and crawl spaces before it reaches your rooms.
On the hottest Pittsburgh days (95F+), some AC systems simply cannot keep up — especially if they are undersized for the home. If your AC always struggles on peak heat days, it may be too small.
🔧 WHEN TO CALL A PRO
Call a pro if the filter is clean, thermostat is correct, outdoor unit is clear, and your home still is not cooling. Refrigerant leaks, compressor issues, and duct problems all need professional equipment to diagnose.