An air conditioner that runs but doesn't cool almost always comes down to one of seven causes: a thermostat setting, a clogged filter, a tripped breaker, a blocked outdoor unit, a frozen coil, low refrigerant, or a failed electrical component. The first five you can check yourself in about twenty minutes - the last two need a technician. Work through this list in order before you call, and you may save yourself the visit.
WHAT TO DO WHEN YOUR AC ISN'T COOLING
Check the thermostat. Set the thermostat to COOL and a few degrees below room temperature, and replace the batteries if it's unresponsive. It sounds obvious, but a thermostat switched to FAN or nudged off its setting is one of the most common "failures" we're called for.
Replace the air filter. A clogged filter restricts airflow and can stop cooling. Swap in a clean filter and recheck the vents. Weak airflow with a cold coil is the classic dirty-filter signature.
Check the circuit breaker. Reset a tripped breaker for the air conditioner. If it trips again, stop and call a professional - a breaker that won't hold points to an electrical fault that isn't safe to keep resetting.
Clear the outdoor condenser. Remove leaves, grass, and debris and keep at least two feet of clearance around the outdoor unit. A smothered condenser can't reject heat, and the system loses capacity fast on hot days.
Check for ice on the coil or line set. If you see ice, turn the system off and let it fully thaw before running it again. Running an iced system risks compressor damage - and ice means either airflow restriction or a refrigerant problem underneath.
Call a professional. If your AC still won't cool, low refrigerant, a failed capacitor, or a bad compressor likely need a technician. Call Boro Mechanical at 717-517-6120.
Checked everything and still warm? Refrigerant, capacitors, and compressors aren't DIY territory. We diagnose the actual fault and fix it - AC repair in Washington Boro, PA and across Lancaster County.
Stop troubleshooting and pick up the phone if the breaker keeps tripping, if you smell burning, if the outdoor unit hums but won't start (a failing capacitor), or if ice returns after a full thaw and a clean filter. Refrigerant work is EPA-regulated and requires certification, and electrical faults inside the condenser can be dangerous. A same-day diagnostic during business hours costs far less than a compressor destroyed by running through a fault. For deeper reading, see our furnace troubleshooting guide or the full resources hub.
FREQUENTLY ASKED QUESTIONS
An AC that runs but won't cool usually points to low refrigerant, a dirty condenser coil, a failing capacitor, or a frozen evaporator coil. Boro Mechanical's technicians diagnose the exact cause across Washington Boro and Lancaster County, then repair it the same visit when parts are on hand. Call 717-517-6120.
A frozen AC coil is almost always caused by restricted airflow or low refrigerant. A clogged filter, blocked return vents, or a refrigerant leak lets the coil drop below freezing. Turn the system off, let it thaw, and call Boro Mechanical at 717-517-6120 to find and fix the cause.
Yes. A clogged filter restricts airflow across the evaporator coil, which can make the AC blow weak or warm air and even freeze the coil solid. Replacing the filter is the first check in any no-cooling situation. If cooling doesn't return after the coil thaws, call Boro Mechanical at 717-517-6120.
STILL NOT COOLING?
Same-day AC diagnostics during business hours across Lancaster County. Honest findings, transparent pricing, repairs done right the first time.
