Furnace problems often arise from lack of maintenance or normal wear and tear on components. Here are the most common issues homeowners face:

Faulty Thermostat

• Digital displays going blank or showing incorrect temperatures indicate thermostat failure
• Wiring problems can prevent proper communication between thermostat and furnace
• Sometimes just needs new batteries or recalibration rather than full replacement

Dirty or Clogged Filters

• Restricted airflow from dirty filters forces furnace to work harder
• Can lead to overheating, short cycling, and increased energy bills
• Filters should be checked monthly and replaced every 3-6 months

Ignition or Pilot Light Problems

• Modern furnaces use electronic ignition systems that can fail
• Older systems with pilot lights may go out due to drafts or thermocouple issues
• Dirty flame sensors can prevent proper ignition

Blower Motor Issues

• Strange noises like squealing or grinding indicate bearing problems
• Motor may run continuously or not at all if capacitor fails
• Regular lubrication helps prevent premature failure

Heat Exchanger Cracks

• Most serious furnace problem due to potential carbon monoxide risks
• Often caused by age or repeated overheating
• Signs include soot around furnace, strange odors, and higher utility bills

Limit Switch Failures

• Safety device that shuts off furnace if it overheats
• Can fail in either open or closed position
• Often triggered by restricted airflow or blower problems

Preventive Maintenance Tips:

• Schedule annual professional inspection before heating season
• Replace filters regularly
• Keep area around furnace clean and unobstructed
• Listen for unusual noises and note performance changes
• Install carbon monoxide detectors
• Check thermostat batteries annually

When to Call a Professional:

• Any gas smell or carbon monoxide concerns
• Electrical issues
• Strange noises or vibrations
• Complete system failure
• Frequent cycling on and off
• Significant increase in utility bills

Cost Considerations:

• Annual maintenance: $80-200
• Thermostat replacement: $150-400
• Ignition system repair: $150-500
• Blower motor replacement: $450-1200
• Heat exchanger replacement: $1500-3500
• Complete furnace replacement: $2500-7500+

Service Life and Replacement:

• Most furnaces last 15-20 years with proper maintenance
• Consider replacement if repairs exceed 50% of new unit cost
• Older units (15+ years) are significantly less efficient
• New high-efficiency models can reduce heating costs by 15-30%

Warning Signs:

• Yellow pilot light instead of blue
• Visible rust or cracks
• Excessive dust or soot
• Uneven heating throughout home
• Rising utility costs despite similar usage
• More frequent repairs needed
• Age exceeding 15 years

By addressing problems early and maintaining regular service schedules, homeowners can extend furnace life and avoid costly emergency repairs. Many issues start small but can lead to significant damage or safety concerns if ignored.