AC not blowing cold air?

What this usually is

• The outdoor unit has lost power while the indoor blower keeps running, so the system moves air it never cooled.
• The refrigerant charge has dropped, which happens through a leak rather than through normal use.
• A filter or coil is loaded heavily enough that the system cannot carry heat out of the house.

When to stop and callIf the outdoor unit still will not start, or the filter was already clean, stop there. What is left is electrical or sealed-system work.

What this usually is

• A tripped breaker, or a blown low-voltage fuse on the control board.
• The condensate safety switch has filled and cut the system off on purpose, to stop an overflow.
• Flat thermostat batteries, on the models that still use them.

When to stop and callIf the breaker trips again after one reset, stop. A breaker that keeps tripping is reporting a fault, not causing one.

What this usually is

• The indoor blower motor or its capacitor has failed while the outdoor unit still receives its call for cooling.
• The control board has stopped sending power to the blower.
• A float switch has tripped and cut the indoor half only.

When to stop and callIf the fan will not run on ON, stop there. Running the outdoor unit with no indoor airflow can freeze the coil and add a second fault to the first.

What this usually is

• Airflow across the indoor coil has dropped far enough that the coil falls below freezing.
• The refrigerant charge is low, which drops that same coil temperature for a different reason.
• A closed, blocked, or crushed return is starving the system of air.

When to stop and callDo not chip, scrape, or heat the ice. If it comes back after a full thaw and a clean filter, the cause sits underneath it and needs gauges.

What this usually is

• The outdoor unit is overheating, and its internal protection shuts it down before damage.
• A dirty condenser coil is holding in the heat the system needs to reject outdoors.
• The system is oversized for the space and satisfies the thermostat faster than it can pull humidity out.

When to stop and callIf it still cycles once the coil is clear, stop. Repeated short cycling is hard on the compressor, which is the expensive part of the system.

What this usually is

• The condensate drain line is clogged, so water backs out of the pan instead of leaving the house.
• The drain pan itself has rusted through or cracked.
• A frozen coil is thawing and shedding more water at once than the drain can carry.

When to stop and callCall once the system is off, particularly if the unit sits in an attic. Water above a ceiling does more damage than the fault that started it.