AC not cooling and AC not blowing cold air troubleshooting guide.
Before assuming the worst, confirm the thermostat is set to COOL with the fan on AUTO and the setpoint at least four degrees below room temperature. Then pull the filter. A filter packed solid strangles airflow across the evaporator coil, which drops capacity, ices the coil and mimics a major failure. Roughly one in six AC not cooling calls resolves at the filter.
This is the single most common cause of an air conditioner not working in summer. The capacitor gives the compressor and fan motor the jolt they need to start. When it weakens you hear a hum or click outside with no fan spin. It is an inexpensive part and a fast repair, but it needs meters to confirm and sits behind live high-voltage terminals. Book AC repair.
The outdoor coil rejects heat. Coat it in grass clippings, cottonwood fluff and dust and the system cannot dump heat, so head pressure climbs and cooling collapses. Gentle rinsing from inside out helps; heavy fouling needs chemical cleaning during an AC tune-up.
Refrigerant is not consumed. If you are low, you have a leak, usually at the line-set, coil or a Schrader valve. Topping off without finding the leak is money burned. Symptoms include weak cool air, ice on the suction line and hissing. Insist on leak detection, not just a recharge.
An AC frozen coil is a symptom, not a cause. Either airflow is restricted or refrigerant is low. Shut the system off, run the fan only for a few hours to thaw, then get it diagnosed. Running a frozen system risks flooding liquid refrigerant back into the compressor.
The contactor is the relay that energizes the outdoor unit. Pitted or welded contacts cause no-starts or a unit that never shuts off. Cheap part, quick swap, big symptom.
If the compressor runs but the top fan does not spin, shut it down immediately. Without airflow the compressor overheats and trips on internal overload, and repeated cycles kill it. A grinding or screeching noise here is the classic AC making noise complaint.
Indoors, a failing ECM module or a blower wheel caked in dust cuts airflow dramatically. You feel weak air at the registers even though the outdoor unit runs fine.
The expensive one. Shorted windings or mechanical seizure means AC compressor repair or, more often on older units, an AC replacement. Always get repair and replace numbers side by side.
If the system tests fine but the house never satisfies, the ducts may be dumping cool air into an attic or crawlspace. That is an HVAC repair and design issue, not an AC failure.
Call immediately for burning smells, breakers that trip repeatedly, ice on the refrigerant lines, or any household with infants, elderly residents or medical needs during a heat advisory. Our emergency HVAC repair line runs 24/7 at (833) 659-2624.
Browse all service locations →
“Emergency AC repair on a Sunday during a heat wave. The dispatcher gave a real arrival window and the tech showed up inside it. Cannot ask for more than that.”
Derrick S.“Our AC quit at 11pm and someone answered the phone right away. A tech was at the house before midnight, found a bad capacitor and had cold air blowing in under an hour. Honest pricing, no runaround.”
Danielle R.“AC was running but not blowing cold air. They found low refrigerant from a line-set leak, repaired it and recharged instead of pushing a replacement. Saved us thousands.”
Ahmed K.Emergency AC repair, same day furnace repair and 24 hour heating repair near you.