Heat Pump Emergency Heat & Aux Heat Guide Birmingham AL

When a freeze hits Birmingham, switching your thermostat to Emergency Heat (often labeled EM Heat) shuts off the outdoor heat pump and heats your home with indoor electric backup strips only. Use it as a short-term backup if your outdoor unit has failed or is buried in ice that will not clear—not just because the weather turned cold.

If your heat pump is not keeping up, blowing cold air, or stuck in Aux Heat, a service call typically runs $80–$350 before parts with a free 15-minute quote. Call (205) 859-0047, Monday–Friday, 8:00am–4:30pm, or book online 24/7. Same-day appointments available.

Aux Heat vs. Emergency Heat: what is the difference?

Thermostats often show both labels, which makes it easy to hit the wrong switch on a cold morning. Here is what each setting actually does:

Aux Heat (Auxiliary Heat)

Aux Heat turns on automatically while your thermostat stays in normal Heat mode. Your outdoor heat pump keeps running, and the indoor electric heat strips kick in for a boost during a hard Birmingham freeze, a defrost cycle, or a quick 3–5 degree thermostat bump.

Emergency Heat (EM Heat)

Emergency Heat is a manual switch you select at the thermostat. It locks out the outdoor unit and runs only your indoor electric heat strips (or backup furnace on a dual-fuel setup). Because those strips use much more electricity than a heat pump, EM Heat is meant only for emergencies until the outdoor unit is fixed.

When to switch to Emergency Heat — and when to leave it on Heat

Leave your thermostat on Heat when:

Temperatures drop into the 20s or 30s and your house stays near the setpoint
Aux Heat flashes on and off during the coldest hours of the morning
Air from your vents feels lukewarm (90°F–100°F) rather than hot like a gas furnace
Light frost forms on your outdoor coil and melts away during a normal defrost cycle

Switch to Emergency Heat and call us when:

Your outdoor unit is silent, tripped off, or making loud grinding or buzzing sounds
Heavy ice encases your outdoor coil or fan blades and never clears
Your indoor temperature keeps dropping even though the outdoor fan is spinning
You need temporary warmth to protect pipes and keep the house livable while waiting for repair

Once the problem is solved, remember to switch your thermostat back from EM Heat to Heat. Leaving a home on Emergency Heat for days can double or triple your winter electric bill.

Safe checks before you call

Before you book a visit, walk through these quick, safe checks at your thermostat, filter, and outdoor unit:

Check thermostat mode and setpoint

Make sure your thermostat is set to Heat (not EM Heat left over from last winter, Cool, or Off). Raise the setpoint a degree or two at a time—jumping 5+ degrees at once forces Aux Heat on immediately.

Inspect your indoor air filter

A dust-packed filter restricts airflow across your indoor coil and heat strips, which can trip high-limit safety switches and shut down backup heat. Swap in a clean filter if yours looks clogged.

Clear leaves or loose snow outside

Gently brush snow, leaves, or loose ice away from the sides and top of your outdoor unit so air can move. Never chip ice off the coil with a screwdriver or force a frozen fan blade.

Check the air handler and outdoor breakers

Your heat pump has two breakers: one for the outdoor unit and one (or a double breaker) for the indoor air handler and heat strips. If a breaker has tripped, reset it once. If it trips again, stop and call us.

Why Aux Heat stays on nonstop—or fails when you need it

Birmingham-area homeowners usually call us for one of two emergency-heat problems during a cold snap: either Aux Heat never shuts off, or Emergency Heat blows cold air when the outdoor unit goes down.

Burned-out heat strip or sequencer

Electric heat kits rely on relays and sequencers to bring elements online. When a strip element burns open or a sequencer fails, your backup heat either blows cold air or only heats at half strength.

Stuck defrost board or sensor

If the defrost control stops triggering—or drops into defrost too often—your outdoor coil packs with ice and forces Aux Heat to carry the entire house alone.

Low refrigerant or reversing valve fault

A heat pump low on refrigerant or with a stuck reversing valve cannot move enough heat indoors, so your thermostat locks onto auxiliary heat strips to make up the difference.

Tripped thermal limit or thermostat wiring

Weak airflow, loose low-voltage thermostat wires, or a failed thermal cutout on the electric heat kit can shut down Emergency Heat right when temperatures drop below freezing.

Heat pump frozen or backup heat not working?

A technician checks both your outdoor heat pump and indoor heat strips and gives you the exact price before any parts or repairs. A service call typically runs $80–$350 before parts with a free 15-minute quote.

Call (205) 859-0047 Request service

Free 15-minute quote · Price before parts · Same-day appointments available

Why Birmingham homeowners call Happeez

Licensed, bonded and insured Alabama HVAC contractor, License #2012153.
32 years of experience, plus 25 years as a master electrician—useful when troubleshooting high-draw electric heat kits and sequencers.
Free 15-minute quote and clear price before any parts or repairs.
Installation labor is backed by a 1-year guarantee; all parts and materials are covered solely by their manufacturer’s warranty.
Local shop within Birmingham city limits with same-day appointments available.
We service all heat pump brands, central split systems, packaged units, and ductless mini-splits.

Reviews: Google · Nextdoor

Heat Pump Emergency Heat FAQ

Not just because it is cold outside. Leave your thermostat in Heat so your outdoor unit keeps running and auxiliary heat steps in automatically when needed. Switch to Emergency Heat only if your outdoor unit has failed, is buried in ice that will not clear, or is blowing cold air and you need temporary warmth while waiting for a repair.

Aux Heat (auxiliary heat) comes on automatically to assist your heat pump during a hard freeze or when you raise the thermostat several degrees. Emergency Heat (EM Heat) is a manual thermostat setting that shuts off your outdoor heat pump and heats your house using only the indoor electric heat strips.

In freezing weather, a heat pump pulls heat from cold outdoor air, so register air naturally feels cooler than furnace heat and the unit runs longer cycles. Brief drops in air temperature during a defrost cycle are also normal. Call for service if the outdoor coil stays iced over, the air turns cold, or your house keeps losing temperature.

A service call typically runs $80–$350. That is an estimate only; minor parts are sometimes included and major parts usually not included. Your technician checks the heat pump and backup heat strips in person and gives you the exact price before any parts or repairs.

Use Emergency Heat only as a short-term backup until your outdoor heat pump is repaired. Electric heat strips draw much more power than normal heat-pump operation and can drive up your electric bill quickly if left on for days.

Get your heat pump and backup heat checked

Free 15-minute quote · Price before parts

Same-day appointments available · Local shop within Birmingham city limits. Phones Mon–Fri 8:00am–4:30pm · Book online 24/7 (request service online and we confirm during business hours). Licensed, bonded and insured, License #2012153.