Troubleshooting
HVAC Short Cycling: Why Your System Turns On and Off Repeatedly
6 min read••
When your HVAC runs for just a few minutes then shuts off, only to restart shortly after, it's short cycling. This is hard on equipment and your energy bills.
A typical AC or furnace cycle should last 15-20 minutes. If your system is running for just a few minutes, shutting off, then restarting, it's short cycling—and it's a problem.
Why Short Cycling Is Bad
- Increased wear on components (especially the compressor)
- Higher energy bills from inefficient operation
- Uneven temperatures throughout your home
- Reduced equipment lifespan
Common Causes
Oversized Equipment The most common cause. An oversized system cools or heats the space too quickly, satisfying the thermostat before completing a proper cycle. Unfortunately, the fix is replacing with correctly sized equipment.
Thermostat Issues - Thermostat in a poor location (hot or cold spot) - Faulty thermostat sending incorrect signals - Thermostat too close to supply vent
Refrigerant Problems Low refrigerant can cause the system to overheat and shut off on safety limits.
Dirty or Frozen Coils Restricted airflow causes the system to work harder and trigger safety shut-offs.
Electrical Issues Failing capacitors, control boards, or wiring problems can cause erratic operation.
Overheating Dirty filters, blocked vents, or failing motors can cause the system to overheat and cycle off.
Diagnosis
Short cycling has many causes, and diagnosis requires systematic troubleshooting. Start with the basics: 1. Check and replace the air filter 2. Ensure all vents are open and unobstructed 3. Make sure the outdoor unit has good airflow
If those don't solve it, professional diagnosis is needed to identify the specific cause.