If you’ve noticed the word “AUX” or “Auxiliary Heat” showing up on your thermostat more often this winter, you’re not alone.
Homeowners across Counce, Pickwick, Savannah, Hardin County, Corinth, MS, and North Mississippi frequently ask about auxiliary heat during colder months. And while it’s completely normal in certain conditions, it can also signal that your system is working harder than it should.
Here’s what auxiliary heat really means — and when it’s worth having your system checked.
What Is Auxiliary Heat?
Heat pumps work differently than traditional furnaces. Instead of generating heat, they transfer heat from the outside air into your home.
Even when it’s cold outside, there’s still some heat energy in the air. However, as temperatures drop — especially during winter cold snaps in West Tennessee and North Mississippi — it becomes harder for the heat pump to extract enough heat efficiently.
That’s when auxiliary heat kicks in.
Auxiliary heat is a secondary heating source (usually electric heat strips) designed to:
Help the heat pump maintain indoor temperature
Support the system during extreme cold
Quickly raise indoor temperatures when needed
When Is Auxiliary Heat Normal?
You’ll typically see auxiliary heat activate:
During freezing temperatures
When the thermostat is raised several degrees at once
During defrost cycles
When recovering from a setback (like overnight temperature drops)
In these situations, AUX heat is doing exactly what it’s designed to do.
When Auxiliary Heat Might Signal a Problem
If auxiliary heat is running frequently — even during mild winter temperatures — that could indicate an issue.
Common causes include:
🔧 Reduced Heat Pump Efficiency
If your system isn’t transferring heat effectively, it may rely more heavily on auxiliary heat.
🌬️ Airflow Problems
Dirty filters, duct leaks, or blocked vents can reduce performance.
❄️ Outdoor Unit Issues
Ice buildup, restricted airflow, or mechanical wear can limit the system’s ability to pull heat from outside air.
⚡ Electrical Component Strain
Capacitors, relays, or sensors under stress may cause improper operation.
Because auxiliary heat relies on electric resistance heating, it uses more energy than the heat pump itself. That’s why frequent AUX operation can lead to higher winter utility bills.
Why It Matters in West Tennessee & North Mississippi
In areas like Hardin County and Corinth, MS, winter temperatures often fluctuate. A system that’s already struggling can shift to auxiliary heat more often during these swings.
If you’ve noticed:
Higher-than-usual energy bills
Longer run times
Uneven heating
AUX heat staying on for extended periods
…it may be time for an inspection.
How to Reduce Auxiliary Heat Usage
To help your system operate efficiently:
Replace air filters regularly
Avoid large thermostat jumps
Schedule seasonal maintenance
Keep outdoor units clear of debris
Address airflow or duct issues
Proper maintenance helps your heat pump handle winter demand more effectively — reducing reliance on auxiliary heat.
When to Call Harbin Heating & Air Conditioning
If auxiliary heat seems to be running constantly or your energy bills have climbed unexpectedly, it’s worth having your system evaluated.
📞 Call Harbin Heating & Air Conditioning — 731-689-3651
📍 Serving Counce, Pickwick, Savannah, Hardin County, Corinth, MS, and all of North Mississippi
We’ll check system performance, airflow, and electrical components to ensure your heat pump is operating efficiently — even during cold snaps.
Auxiliary heat is a helpful backup.
It shouldn’t become your system’s main source of heat.
