Top-rated independent heating and cooling across central Arkansas and the Arkansas River Valley
Heat Pump Running Nonstop in Cold Weather
Your heat pump has been running for hours without shutting off, the house feels a little cool, and you are wondering if something broke. Long run times in cold weather are often normal for a heat pump. Nonstop running with a house that never warms up is not. Here is how we tell the difference, what you can safely check yourself, and when to call us.
Call (888) 365-6280- A real person answers
- Open 7 days
- Written quote before work starts
Taking calls until 5:00 PM CT
Rock City Air Systems service team · field-reviewed before publishing
What Nonstop Running Actually Means
A heat pump pulls heat out of outdoor air, so the colder it gets outside, the less heat it moves per minute and the longer it runs to hold your setpoint. On a 30 degree morning, run times of an hour or more are expected, and a variable-speed system may simply never fully stop. The symptom that matters is temperature, not run time. If the thermostat reads within a degree or two of what you set and the air from the vents feels warm, the system is doing its job. If the house keeps drifting down while the unit runs, something is limiting capacity and it needs looking at.
Cause One: Airflow and Settings, the Cheap Stuff First
Most nonstop-running calls we take across Arkansas, Tennessee, Mississippi and Texas start with restricted airflow or a thermostat doing something the homeowner did not intend. A loaded filter, closed or blocked vents, and returns covered by furniture all cut the air the system needs to move heat. On the thermostat side, emergency heat left on, a program schedule nobody remembers setting, or a fan set to ON instead of AUTO all look like a system that never stops. In mid-century homes with ducts run through unconditioned attics, leaky or crushed flex duct dumps warm air where nobody lives, and the equipment runs forever trying to make up the loss.
Cause Two: Outdoor Unit Icing and Defrost Trouble
Heat pumps grow frost on the outdoor coil in cold, damp weather, and that is why they have a defrost cycle that briefly reverses and melts it off. Humidity across the region keeps that cycle busy all winter. When the defrost board, sensor or reversing valve fails, the coil turns into a block of ice, airflow across it stops, and the system runs constantly while delivering almost nothing. A light coat of frost that clears on its own is normal. Solid ice covering the coil, or ice that is still there hours later, means the defrost side needs a technician. Do not chip or pour hot water on it.
Cause Three: Refrigerant Charge, Compressor and Auxiliary Heat
A heat pump low on refrigerant still runs, it just cannot move much heat, so it runs and runs while the house slides. Charge problems come from leaks, and leaks are a repair, not a top-off you should schedule every winter. A compressor or reversing valve that has lost efficiency shows the same way. Then there is auxiliary heat. Electric strips or a gas furnace in a dual fuel setup are supposed to carry the load when the outdoor temperature drops below the balance point. If that stage is not coming on, the heat pump is left running alone against weather it cannot handle. Refrigerant and high-voltage work stay with us.
What You Can Safely Check, and What We Do Differently
Safe homeowner checks: put fresh batteries in the thermostat and confirm it is set to HEAT with the fan on AUTO, look for a tripped breaker, change the filter, make sure supply and return vents are open and clear, and pull leaves, grass clippings or snow drifts back from the outdoor unit. That is the list. If you smell gas or your carbon monoxide alarm sounds, get everyone outside first, call 911 or your gas utility, then call us. On our side we measure temperature rise across the coil, check static pressure, read refrigerant pressures and superheat, test the defrost board and sensors, and verify the auxiliary heat stage actually energizes at the right outdoor temperature.
Heat Pump Running Nonstop in Cold Weather — common questions
Is it bad for a heat pump to run all day in winter?
Not by itself. Long, steady run times are how heat pumps are designed to work in cold weather, and they are easier on the equipment than short cycling. The problem is running nonstop while the house still loses temperature.
Should I switch to emergency heat if it runs constantly?
Only if the heat pump has clearly quit or the outdoor coil is iced solid. Emergency heat is straight electric resistance and costs far more to run. Use it briefly to stay warm, then call us for heating repair.
Why is the air from my vents cooler than my old furnace?
Heat pump supply air normally runs cooler than furnace air, often in the 90s, so it can feel drafty even while working correctly. If it feels close to room temperature or cooler than that, have it checked.
How it works
- Step 1
Tell us the symptom
Call or fill out the quote form and describe what the system is doing. Warm air, short cycling, water on the floor, a smell, a noise. That detail tells us what parts to load on the truck.
- Step 2
We diagnose on site
A technician checks the thermostat, the electrical side, airflow through the filter and coil, refrigerant behaviour and the ductwork. You hear what we found in plain language before anything gets replaced or repaired.
- Step 3
You approve the fix
We explain the repair, what it costs and what happens if you wait a season. Nothing gets done without your go-ahead, and we tell you honestly when a repair no longer makes sense.
- A real person answers
- Open 7 days
- Written quote before work starts
Why homeowners call us
- We know humid-climate systemsAcross the region the real enemy is moisture. Systems here run long hours pulling water out of the air, and that shows up as frozen coils, clogged drains and mildew smells. We diagnose for humidity, not just temperature.
- Mixed gas and heat pump workPlenty of homes we visit run a heat pump with gas backup, and the two have to hand off cleanly. We troubleshoot both sides, including defrost boards, reversing valves, ignitors and heat exchanger concerns.
- Attic ductwork is our daily breadMid-century homes often have ducts running through attics that hit brutal temperatures. Crushed runs, disconnected boots and leaking joints steal cooling before it reaches the room. We find them instead of blaming the equipment.
- Repair before replaceA capacitor, a contactor, a blower motor or a clogged drain line fixes a lot of the calls we take. We would rather fix what you have and tell you plainly when the numbers stop working.
- All major brands, gas & electricFrom Carrier and Trane to Lennox, Goodman, Rheem and Bryant, serviced independently.
- Straight answersNot worth fixing? We say that out loud, and often it saves you the visit fee.
About this guide
If the safe checks didn't fix it, the fault is real
Describe what you found and we'll take it from there. Booking takes about a minute.
- A real person answers
- Open 7 days
- Written quotes
- All major brands
- Gas & electric
Rather not call? Get a free quote →