Thermostat and system short cycle, turning on and off frequently without reaching setpoint.

Safety first: No internal high-voltage work is required for thermostat settings.

• Step 1 – Adjust cycle rate: In thermostat settings, reduce the number of cycles per hour or increase minimum run time if options are available.
• Step 2 – Check placement: Ensure thermostat is not directly in the path of supply air, which can cause it to sense rapid temperature changes.
• Step 3 – Seal wall drafts: Seal the wall opening behind the thermostat to prevent drafts from affecting the sensor.
• Step 4 – Monitor operation: After adjustments, observe system behavior over several hours.
• When to call a pro: If short cycling persists, equipment sizing or internal furnace/AC safeties may be involved and should be evaluated by a technician.