Why did the AC pick the hottest week to die?

Because heat is load, and load finds the weak part. Capacitors, contactors, marginal charge and matted coils all survive May and fail together in the first real heat wave. It is the most predictable failure date on the Alabama calendar.

The unit hums but nothing spins, is it dead?

Very often that is a failed run capacitor: a small, inexpensive part with an August habit. It looks like a dead system and is frequently a twenty-minute repair, which is exactly why it deserves a measured diagnosis before any talk of replacement.

Why does my AC run all day and the house never gets to the set temperature?

In this climate that is most often a leaking attic duct or a coil that has lost its charge, not a unit that has fallen behind on a hot day. A supply run that has come loose in the attic dumps cool air into the insulation instead of the living room, so the system runs on and on while the thermostat barely moves; a low charge produces the same symptom because every cycle is moving less heat than it should. Both show up the same way at the register and need a different fix, which is why it is worth a technician checking pressures and airflow before anyone talks about a bigger unit.

Is it worth repairing an old AC, or should I just replace it?

Some shops in the trade lean on a simple threshold: age of the unit times the repair estimate, checked against roughly five thousand dollars. Come in under that and the repair is usually still the sensible move; land well above it and the same money tends to go further toward a new system. A four-year-old unit needing a six-hundred-dollar contactor is nowhere near that line; a nineteen-year-old compressor quoted at two thousand is past it. It is a starting point for the conversation, not the whole of it, a unit that just had major parts replaced can be worth pushing a little further past the number.

AC repair

When an air conditioner quits in an Alabama July, the household is not shopping for philosophy. It is hot. But the ten minutes a technician spends measuring instead of guessing is what separates a inexpensive afternoon from a four-figure one, and it is worth knowing what those ten minutes should contain.

What a real service call covers

The electrical suspects first, because August kills them first: the run capacitor measured against its rating, the contactor checked for pitting, the compressor’s draw read. Then the loop: refrigerant charge measured, never assumed, with a temperature split across the coil to confirm what the gauges say; the outdoor coil inspected for the pollen, grass and cottonwood that blanket it by midsummer; and the condensate line, because in Gulf humidity a clogged drain shuts down more systems than compressors do.

The distinction that matters most is between repairing and refilling. Refrigerant does not get used up: a low system has a leak, and a top-up without a leak search is the same service call sold twice. On older units running phased-out refrigerant, the honest conversation shifts to replacement, because the refill alone can rival the value of the machine holding it.

Repair or replace, in a hundred-day season

The arithmetic runs on hours, not birthdays. A young system with a failed capacitor or fan motor is a repair: weather takes wear parts, and Alabama weather takes them on schedule. A compressor or coil failure on a unit deep into its Alabama hours is a different case: a large repair on equipment whose every other component has the same career behind it, facing another hundred-day season the moment it is fixed.

Either way, what protects you is a written finding: what failed, what was measured, what it costs, and what the technician would do in their own house. A visit that ends in a number without findings is a quote, not a diagnosis, and in a heat wave, when every shop’s phone is ringing, the written finding is also what makes a second opinion possible at all.

The season is not a figure of speech. Over the last decade NOAA’s records put Montgomery at roughly a hundred days a year at or above ninety degrees, with Birmingham and Huntsville both past seventy. A system that quits in the middle of that is not a scheduling inconvenience, and it is why this conversation so often happens under pressure.

Quick answers

Why did the AC pick the hottest week to die?: Because heat is load, and load finds the weak part. Capacitors, contactors, marginal charge and matted coils all survive May and fail together in the first real heat wave. It is the most predictable failure date on the Alabama calendar.
The unit hums but nothing spins, is it dead?: Very often that is a failed run capacitor: a small, inexpensive part with an August habit. It looks like a dead system and is frequently a twenty-minute repair, which is exactly why it deserves a measured diagnosis before any talk of replacement.
Why does my AC run all day and the house never gets to the set temperature?: In this climate that is most often a leaking attic duct or a coil that has lost its charge, not a unit that has fallen behind on a hot day. A supply run that has come loose in the attic dumps cool air into the insulation instead of the living room, so the system runs on and on while the thermostat barely moves; a low charge produces the same symptom because every cycle is moving less heat than it should. Both show up the same way at the register and need a different fix, which is why it is worth a technician checking pressures and airflow before anyone talks about a bigger unit.
Is it worth repairing an old AC, or should I just replace it?: Some shops in the trade lean on a simple threshold: age of the unit times the repair estimate, checked against roughly five thousand dollars. Come in under that and the repair is usually still the sensible move; land well above it and the same money tends to go further toward a new system. A four-year-old unit needing a six-hundred-dollar contactor is nowhere near that line; a nineteen-year-old compressor quoted at two thousand is past it. It is a starting point for the conversation, not the whole of it, a unit that just had major parts replaced can be worth pushing a little further past the number.

A hundred days of load find the weakest link. It is almost never the box out in the yard. Where the work actually happens in the house.

Tap to enlarge

1 Thermostat. Where the season’s mileage actually accumulates.
2 Return and filter. Undersized in half the retrofits, and the reason the far room never cools.
3 Air handler and furnace. The part of the system Alabama barely uses, and almost never checks.
4 Coil and condensate drain. Liters of Gulf moisture a day, all leaving through one narrow line.
5 Attic ducts. Conditioned air, routed through the hottest space in the building.
6 Outdoor unit. Where a Gulf-coast August decides which capacitors see another summer.

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