Why does the outdoor unit cycle off before the indoor fan?

Two Different Jobs, Two Different Shutdown Rules

The outdoor unit and the indoor blower are doing genuinely different work, so it makes sense they don't stop at the same instant. The compressor's job is compressing refrigerant, real work that has nothing left to contribute the moment the thermostat is satisfied, so it shuts down right away. The indoor blower's job is simpler: move air, and it can keep doing that safely for a little while after the compressor stops, which is exactly what most systems are set up to have it do. That's the whole logic behind the delay.

What Happens During Those Extra Seconds

The evaporator coil doesn't instantly stop being cold the moment the compressor shuts off. For a short window afterward it's still colder than the air passing over it, and the indoor blower uses that window to keep pushing the last of that cooled air into the house rather than leaving it to fade away in the ductwork. Most systems hold the blower on for roughly a minute or so past shutoff before it powers down too. From inside the house, that's the moment the outdoor hum goes quiet while air keeps coming from the vents for a few seconds longer, exactly what's supposed to happen.

It's a small efficiency gain built into how the system is programmed to sequence itself, and it's also why the delay is measured in seconds rather than minutes: a blower running a long stretch across a coil that's still wet starts pulling moisture back into the house instead of pushing out cold air. That setting lives on the control board, not on the thermostat, so it isn't something a homeowner changes.

Why the Delay Length Isn't the Same on Every System

Not every system holds that blower on for the exact same length of time. Some equipment has a fixed delay hardwired into the control board, while other systems let an installer adjust it slightly during setup, and staged or variable-speed equipment sometimes ramps the blower down gradually instead of cutting it off all at once. All of those are still versions of the same idea: give the coil's remaining cold air somewhere useful to go before the blower shuts down too.

That's why two neighbors with different brands of equipment can describe slightly different timing for the same basic behavior and both be describing something completely normal. What matters isn't the exact number of seconds, it's whether the outdoor unit stops cleanly and the blower follows shortly after, rather than either one behaving erratically.

How to Tell This Apart From an Actual Problem

This sequencing only describes the normal end of a cooling cycle: the outdoor unit stopping cleanly while the blower finishes up seconds later. It's a different situation entirely if the outdoor unit shuts off and restarts repeatedly within the same short stretch while the thermostat is still calling for cooling, or if the indoor blower never stops at all regardless of whether the house is cool. Both of those are their own separate issues, not the sequencing described here.

If what you're hearing doesn't match a single clean stop followed by the blower finishing up shortly after, mention it to a technician. An AC repair visit starts with a $150 diagnostic that pins down which part of the cycle is actually behaving differently than it should, with an upfront quote before anything gets fixed.