Auxiliary Heat on a Wesley Chapel Heat Pump

Repair Guide By Tim Hawk, Licensed HVAC Contractor · CAC1816515 • Oct 23, 2026 • 8 min read

Quick Answer

AUX on the thermostat in December means the strips are on. When that is normal in Wesley Chapel, and when it is a repair.

Start here before you book service

✓ AUX for a few minutes on a cold start can be normal.
✓ AUX all evening on a mild December afternoon is not.
✓ Emergency heat is the strips only. Put the mode back to Heat after a test.
✓ Below about 35°F the strips are backup, not the all-day setting.
✓ A heat test should record whether the outdoor fan ran while AUX was on.

Sounds like you need a tech?

(813) 395-2324

AUX means the strips are helping

Auxiliary heat on a Wesley Chapel thermostat is the electric strips inside the air handler. The heat pump is still the main heat. The strips come on when the room is far below the setpoint, or when the outdoor air is cold enough that the heat pump cannot close the gap alone. The screen says AUX, auxiliary, or sometimes emergency, and those words are not the same thing.

December at the Tampa station is the first month heating degree days pass cooling degree days: a high of 73.9°F, a low of 55.9°F, 105 heating degree days, and 102 cooling degree days (Florida Climate Center, 1991-2020). People in the United States search "auxiliary heat" about 6,600 times a month. In December 2025 that count was about 18,100 (Google Ads, United States). It is not a Wesley Chapel volume. "Heat pump repair Wesley Chapel" stays at the ads floor of 10.

When AUX is the normal start

On a cold morning the thermostat can call the strips for a few minutes while the heat pump catches up. The outdoor fan should still run if the mode is Heat. The supply air gets warm. AUX then drops off. That sequence is a heat pump doing its job in Meadow Pointe or Seven Oaks.

Below about 35°F the strips are the backup. A Wesley Chapel afternoon in December is often in the 70s, so an all-day AUX light on a mild day is not that backup. It means the heat pump never took the call, the lockout is set too high, or the thermostat was left on emergency heat. Emergency heat skips the outdoor unit. The strips carry the house, and the electric bill shows it.

What to write down

Set the mode to Heat. Set the fan to Auto. Note whether the outdoor fan runs while the screen says AUX. If the outdoor unit stays off and the strips run through a 70-degree afternoon, stop there. The repair is the control or the thermostat, not another bag of refrigerant. The page for a system that never warms is heat pump not heating. The shop page is heating service. Call (813) 395-2324. Hours are Monday through Friday 8 a.m. to 6 p.m. and Saturday 10 a.m. to 4 p.m.

Tim Hawk

Owner & Master HVAC Technician · Florida License CAC1816515

Tim founded I Care Air Care in 2010 after 30+ years in the Tampa Bay HVAC trade. EPA Universal certified. The source for all technical guidance published on this site.

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Frequently asked about heating service

Common questions we hear from Wesley Chapel, Tampa Bay, and Pasco County homeowners.

What does auxiliary heat mean on my thermostat?

AUX means the electric strips in the air handler are on. A few minutes at the start of a cold morning can be normal if the outdoor fan is also running. AUX all day on a mild afternoon is a repair.

Is emergency heat the same as auxiliary heat?

No. Emergency heat runs the strips and skips the outdoor unit. Auxiliary heat can run with the heat pump. Put the mode back to Heat after any test. Leaving emergency heat on is a high electric bill.

When does December need the strips in Wesley Chapel?

Below about 35°F the strips are backup. Tampa's December normal is 73.9°F by day and 55.9°F at night, and heating degree days pass cooling degree days that month (Florida Climate Center, 1991-2020). A 70-degree afternoon should not stay on AUX.