My AC keeps switching on and off every few minutes — what causes short-cycling and does it matter?

Short answer: short-cycling — the AC starting and stopping every few minutes — means it keeps hitting a cut-off before it should. The common causes are an oversized unit, low refrigerant, a dirty coil/filter, or a thermostat problem/placement. It matters: all those hard starts wear the compressor, it wastes energy, and it leaves the air clammy because the unit never runs long enough to dehumidify.

The usual causes, easiest to check first: 1. Dirty filter / iced or dirty coil — restricts airflow, the unit trips on protection, then restarts. Clean the filter; if the coil's iced or filthy it needs a service. (Cheapest, check first.) 2. Low refrigerant (a leak) — trips the compressor's low-pressure protection, so it short-cycles. This ties to the leak-not-top-up issue — a leaking unit cycles. 3. Thermostat — faulty, or placed in a draught / near a cold vent so it satisfies too quickly and cuts out. 4. Oversized unit — a too-big AC cools the room in a flash, hits setpoint, shuts off, then restarts — chronic short-cycling with clammy air. This is exactly why correct sizing matters (over-sizing is as bad as under-sizing).

Does it matter? Yes — the compressor hates frequent hard starts (it's the most expensive part), you burn energy on every startup surge, and you get clammy-cool rooms because it never runs a full dehumidifying cycle. So it's wasteful and wearing, not just annoying.

You can check: the filter (clean it) and the thermostat placement. Straight to a tech if the filter's clean and it still cycles — that points to refrigerant/coil/electrical. Running an oversized or short-cycling unit long-term costs you on the summer bill and in compressor life. What did people's short-cycling turn out to be — usually the gas?