The fan sounds exactly as it always has, air is moving out of the vents, and yet the room never drops a degree. It is the single most common call our phone takes between June and September, and nine times out of ten it comes down to one of three things.
The first is a failed run capacitor. It is a small component whose only job is to give the compressor the kick it needs to start turning. When it dies, the fan carries on happily while the compressor sits still — which is precisely why the unit sounds healthy and cools nothing.
The second is a condenser face packed with dust, grass clippings and cottonwood. Heat has to leave the refrigerant somewhere, and a blocked coil is a blanket over the only exit. The third is a refrigerant charge that has slowly walked out through a weeping joint.
Pressures separate the three within twenty minutes, and only one of them is expensive. That is the whole argument for measuring before fitting anything.
