HVAC Running Constantly? Causes & Solutions
When your HVAC runs non-stop but never reaches the desired temperature, you're wasting energy and putting excessive wear on your system. Several issues can cause this frustrating problem.
Signs & Symptoms
Possible Causes
- -Undersized HVAC system
- -Extreme outdoor temperatures
- -Air leaks in home
- -Inadequate insulation
- -Duct leaks
- -Low refrigerant
- -Dirty filters or coils
- -Thermostat location issues
- -Fan set to "on" instead of "auto"
DIY Troubleshooting Steps
Try these steps before calling a professional (unless it's an emergency):
- 1Check thermostat fan setting (should be "auto")
- 2Replace dirty filter
- 3Check for obvious air leaks (windows, doors)
- 4Verify all vents are open
- 5Make sure nothing is blocking outdoor unit
- 6Adjust temperature expectations during extreme weather
When to Call a Professional
- !System ran constantly even in mild weather
- !Suspect system is undersized
- !Need duct leak testing
- !Refrigerant levels may be low
- !Coils need professional cleaning
- !Want load calculation for proper sizing
Estimated Repair Costs
Diagnostic: $89-$200
Minor Repair: $150-$400
Major Repair: $500-$15,000
Repairs vary from filter/coil cleaning to complete system replacement if undersized.
Prevention Tips
Frequently Asked Questions
Is it bad for my HVAC to run constantly?
Yes. Continuous running increases energy costs by 20-40% and accelerates wear on components. Systems are designed to cycle on and off - constant running indicates a problem.
How do I know if my HVAC is undersized?
Signs include: never reaching set temp, constant running, being right-sized in mild weather but failing in extreme temps. A load calculation by a professional determines proper sizing.
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