Definition
Short cycling is when an air conditioner, heat pump or furnace starts and stops in rapid, frequent cycles instead of completing normal run times. Common causes include oversized equipment, a clogged filter, a frozen evaporator coil, incorrect refrigerant charge, an overheating furnace and a misplaced or failing thermostat. It adds wear and reduces comfort and efficiency.
Why it matters to you
With a short cooling season, oversizing is the classic Pacific Northwest AC mistake: an oversized system cools the house in minutes and shuts off before it evens out room temperatures or removes moisture. A furnace or heat pump that short-cycles through a cold, damp winter adds start-up wear to its igniter, compressor and blower.
Practical guidance
Check that the filter is clean and that the thermostat is not near a supply register, sunny window or lamp. If cycling continues, have a technician check airflow, refrigerant charge and safety controls, and for a replacement ask that the system be sized with a Manual J load calculation.
About this definition
Written by the Home Energy Group team — a family-owned HVAC company celebrating 25 years of comfort & care across SW Washington and the Portland metro, licensed in Washington (WA LIC# HOMEEGI003J7) and Oregon (OR CCB# 184255). Definitions inform; an on-site diagnosis decides.
