Heat Pump Down at 3am in January? We Answer.
Emergency heat pump repair across the east corridor — Leeds, Trussville, Moody, Pinson, Clay, Springville. Reversing valve service, defrost board diagnostics, balance-point and auxiliary heat lockouts. Same-truck repair on most calls when parts are in stock. Live answer 24 hours a day, every day of the year. Written estimates before any work begins.
Call (205) 206-5252 NowJohn, 25-year HVAC tech. AL HVAC licensed, bonded, insured. EPA Section 608 Universal certified.
24/7 Live Answer
Reversing Valve Service
Defrost Board Diagnostics
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How a Heat Pump Actually Fails on a Cold Night
Heat pump failures fall into a few repeating patterns. Knowing what is happening helps you describe the problem clearly on the phone and helps the dispatched technician arrive with the right parts. Here are the six failure modes we see most often in Birmingham east-corridor homes during winter.
No Heat — Cold Air Blowing
Heat pump running but blowing cold air at the supply registers means the reversing valve is stuck in cooling mode, or the auxiliary heat strips never engaged. Either is a real winter emergency.
Stuck in Defrost — Long Cycles
A defrost cycle that never ends — outdoor unit fan off, indoor strips running, then nothing — points to a defrost board failure or a stuck defrost thermostat sensor.
Aux Heat Running Constantly
Emergency or auxiliary heat is supposed to kick in only below balance point. If it runs all the time, the heat pump compressor or outdoor sensor has failed and you are paying electric resistance prices.
Outdoor Unit Iced Solid
Some frost on a heat pump in winter is normal. A solid block of ice means defrost failed completely. Running the system makes the damage worse and can crack the outdoor coil.
Compressor Won't Start
Hard-start kit failure, run capacitor failure, reversing valve solenoid bound, or compressor internal failure. We measure capacitor microfarads, contactor resistance, and compressor amperage to isolate.
Thermostat Locked on Emergency Heat
Sometimes a homeowner accidentally engages Em Heat mode on the thermostat and forgets. Power bills triple. We always check the thermostat configuration first.
The Reversing Valve Is the Heart of a Heat Pump
What makes a heat pump different from a straight air conditioner is one component: the four-way reversing valve. In cooling mode the valve sends hot, high-pressure refrigerant to the outdoor coil and routes cool, low-pressure refrigerant to the indoor coil. In heating mode the valve flips — hot refrigerant goes indoors, cool refrigerant goes outdoors and pulls heat out of cold ambient air.
That valve is moved by a small solenoid coil and a slide piston. When the valve fails, it usually fails stuck in cooling mode. The compressor still runs, the fans still blow, but the indoor unit blows cold air during winter while the outdoor unit blasts heat. Diagnosis is straightforward — we measure refrigerant line temperatures with a clamp-on thermometer and check whether the suction and discharge lines are reversed for the calling mode. The fix is either replacing the solenoid coil (cheaper) or replacing the entire reversing valve (more expensive, requires refrigerant recovery and brazing).
Defrost Cycles That Never End
Birmingham winters do not get cold enough often, but on the cold nights they get cold enough for frost to build on the outdoor coil. A heat pump runs an automatic defrost cycle to clear that frost: every 30-60 minutes the reversing valve flips to cooling mode briefly, the outdoor fan stops, and the outdoor coil warms up enough to melt the frost. While that happens, the indoor auxiliary heat strips engage to keep the supply air warm.
Defrost is triggered by a temperature sensor on the outdoor coil and timed by the defrost board. When the defrost board fails or the sensor sticks, defrost either never runs (coil ices over) or runs constantly (system flips back and forth, never builds heat). Either failure shows up first as comfort complaints — the house never gets warm.
Auxiliary Heat — Friend and Enemy
Most Birmingham heat pumps include electric resistance heat strips in the indoor air handler — usually 5kW, 7.5kW, 10kW, or 15kW depending on home size. Those strips engage as supplemental heat when the heat pump alone cannot keep up. They are also the emergency fallback if the heat pump compressor fails entirely.
The problem: electric resistance heat costs roughly three times what heat pump operation costs in the Birmingham climate. A heat pump running normally at COP 3.0 delivers 3 BTU of heat for every 1 BTU of electricity. Resistance strips deliver 1 for 1. So a heat pump that fails and runs on emergency strips alone for a month can triple your January power bill — and many homeowners do not realize the system is failing until the bill arrives.
On every emergency call we check the thermostat configuration first to confirm aux heat is not stuck on, then measure outdoor temperatures and indoor demand to verify the heat pump is actually engaging. If aux is doing the heavy lifting on a 35 °F day, the heat pump is broken.
What to Do Before We Arrive
- Set the thermostat to Emergency Heat. If the heat pump is failing, Em Heat forces the system to run on resistance strips alone. The heat is expensive but it is heat.
- Keep the outdoor unit clear. Brush snow or ice off the top of the outdoor unit if accessible. Do not pour hot water on a frozen coil — thermal shock can crack the fins.
- Check the air filter. A clogged filter restricts airflow and triggers high-temperature lockouts that mimic real failures. Change it before we arrive.
- Note any error codes. Modern heat pump thermostats display fault codes. Photo any code shown and we look it up before we roll.
- Verify the breaker. Heat pump systems often run on two separate breakers — one for the outdoor unit, one for the air handler with the strips. Check both.
East-Corridor Coverage
We dispatch heat pump emergency repair through Leeds, Trussville, Moody, Pinson, Clay, and Springville. East side only — we do not cover the metro at large.
Related work on this site: our main heat pump service page, general heating repair, and the 24/7 emergency dispatch page. For background reading, see our guide on breaker trips.
Heat Pump Emergency FAQ
How is a heat pump emergency different from an AC emergency?
Heat pumps run a reversing valve to switch between cooling and heating modes. That valve, the defrost system, the auxiliary heat strips, and the dual-fuel handoff logic are all heat-pump specific and require different diagnostic skills than straight cooling. A heat pump failing in heating mode at 25 °F is a winter emergency — the auxiliary strips alone often cannot keep up if the heat pump compressor is down. Call (205) 206-5252 24/7.
My heat pump is blowing cold air during winter — is it broken?
Maybe. Heat pumps deliver supply air around 90-95 °F in heating mode, which can feel cool against 98.6 °F skin even when the system is working correctly. The diagnostic question is whether the supply air is warmer than ambient (working) or the same as return-air temperature (not working). If you can measure with a thermometer, point it at the supply register and at the thermostat. More than 20 °F split says the system is heating. Less than 10 °F says something is wrong.
Why is my outdoor unit covered in ice?
During heating mode the outdoor coil is the cold side and the indoor coil is the warm side, reversed from cooling mode. Frost on the outdoor coil is normal. The system runs an automatic defrost cycle every 30-60 minutes that reverses to cooling briefly, heats the outdoor coil, and melts the frost. If defrost fails — bad defrost board, stuck defrost thermostat, or low refrigerant — the frost grows into ice and chokes airflow. Call us before the ice cracks the coil fins.
What is "balance point" and why does it matter?
Balance point is the outdoor temperature at which a heat pump can just barely keep up with the home heating load on its own. Below balance point, auxiliary heat strips engage to supplement. For most Birmingham homes balance point falls between 28 °F and 35 °F. A thermostat that engages aux heat too aggressively burns through electricity. A thermostat that does not engage aux heat soon enough leaves the house cold. Per ENERGY STAR heat pump guidance the auxiliary heat lockout setting is one of the single biggest factors in winter operating cost.
How quickly can you reach Trussville or Leeds in a heat pump emergency?
We dispatch from the east-corridor service area and answer the phone live. Travel time depends on your specific address and current call queue. We do not guarantee response time on the website because guarantees are how dispatchers lie to homeowners. Call (205) 206-5252 — we give you a real estimate when you book.
Will my heat pump warranty cover the repair?
Most major brand heat pumps carry a 10-year parts warranty when registered with the manufacturer. Labor is typically separate. We check warranty status on every call before quoting parts. Even out-of-warranty repairs run cheaper than running on emergency aux heat for a full winter — the math is rarely close.
Heat Pump Down Right Now?
Live answer 24 hours a day. Written estimates before any work begins. East corridor only.
(205) 206-5252