Furnace starts and stops frequently, with very short run times and uneven room temperatures

Safety first: Ensure all safety devices remain connected while troubleshooting.

Steps:

• Check filter and vents: Replace dirty filters and open all vents to reduce overheating and limit trips.
• Review thermostat location: Make sure the thermostat is not near supply registers, direct sunlight, or exterior doors.
• Adjust thermostat settings: Some thermostats allow adjustment of cycle rate or differential. Set according to the furnace capacity and manufacturer recommendations.
• Consult a professional: If the furnace is significantly oversized, a technician can evaluate options such as staging, modulation, or system redesign.