On this page
What goes wrong with heat pumps most often?
Heat pumps are refrigeration systems running in reverse, so their failures look familiar: low refrigerant from a slow leak, a failed capacitor or contactor, a stuck reversing valve, a worn compressor, or airflow choked by a dirty filter or blocked outdoor coil. The thermostat and its settings cause a surprising share of calls too.
This page covers ducted (central) heat pumps — the kind that uses your home’s ductwork like a furnace does — not ductless mini-split systems. In the Puget Sound climate, a well-sized ducted heat pump handles most of the heating season efficiently, switching to auxiliary heat only during the coldest stretches. When that balance breaks down, the symptoms below are what homeowners notice first.
What are the warning signs your heat pump needs repair?
Watch for these patterns:
- Blowing cold or lukewarm air in heat mode — the system runs but never warms the house; often the reversing valve, refrigerant charge or auxiliary heat.
- Outdoor unit iced over and staying that way — some frost during defrost cycles is normal; a unit encased in ice that never clears is not.
- Running constantly without reaching setpoint — heat pumps run long cycles by design, but never satisfying the thermostat points at low refrigerant, a failing compressor or undersized equipment.
- Auxiliary or emergency heat stuck on — if the thermostat shows aux heat during mild weather, something is forcing the expensive backup on.
- New noises — grinding or squealing from the outdoor unit, loud buzzing from a contactor, or rattling panels.
- Ice on the indoor coil or water around the air handler — airflow or refrigerant issues showing up inside.
Note the outdoor temperature when symptoms appear. A heat pump that struggles only below freezing is telling a different story than one that cannot heat on a mild day — and that detail helps the provider diagnose faster.
What can you safely check before calling?
These checks are safe for a homeowner and resolve a fair share of heat pump calls:
- Thermostat mode — confirm Heat mode (not Cool or Emergency Heat) and a setpoint above room temperature. Emergency heat should only be used on purpose, not left on.
- Filter — check and replace a dirty filter. Restricted airflow hurts heat pumps more than most systems.
- Breakers — check the breakers for the indoor air handler and the outdoor unit. Reset a tripped breaker once; if it trips again, leave it off.
- Outdoor unit clearance — clear leaves, snow, ice and stored items from around the unit. It needs a couple of feet of breathing room on all sides.
- Vents and registers — open closed supplies and unblock returns so the system can move air.
Do not open refrigerant lines, adjust the reversing valve or bypass defrost controls. If the checks above do not help, the system needs gauges and meters — which is what the visit below covers.
What happens during a heat pump repair visit?
The provider verifies the symptom, then tests in order: thermostat and control signals, power and safeties, refrigerant pressures and temperatures, the reversing valve, defrost operation, the compressor and fan motors, and airflow through the indoor coil and ducts. Heat pump diagnosis is methodical because several failures share the same symptoms.
You should get a plain explanation of the failed part and a written estimate before work starts. Common repairs such as capacitors, contactors, sensors or a reversing valve are often completed the same visit once approved.
What is auxiliary heat, and why is my unit iced up?
Most ducted heat pumps in this region have electric auxiliary heat strips that kick in when the heat pump alone cannot keep up — during defrost cycles or the coldest nights. Seeing "aux heat" on the thermostat occasionally in deep winter is normal. Seeing it constantly in mild weather means the heat pump is not carrying its share, and the electric strips are doing expensive work they should not be doing.
As for ice: the outdoor coil frosts up in cold, damp air and the system periodically reverses to melt it off — you may see steam and hear the unit change tone during defrost, which is normal. What is not normal is a unit that stays iced over, never seems to defrost, or has ice bridging the fan. That points at a defrost control, sensor or refrigerant problem worth a call.
When is repair no longer the right call?
Repair is sensible when the system is otherwise healthy and the failure is a wear part. Replacement deserves a serious look when the compressor itself is failing, when refrigerant leaks keep returning, or when the system is old enough that a new unit’s efficiency would noticeably change winter bills.
Because heat pumps both heat and cool your home, their economics differ from a furnace-only decision — ask the provider to lay out repair cost against replacement cost and what each path means for year-round comfort, then decide with both numbers in front of you.
Furnaces and heating in Bothell homes
Bothell sits in the Sammamish River valley, and on clear winter nights cold air settles into the low areas — valley homes can run several degrees colder overnight than the hillsides above them. The housing mix runs from older valley homes to newer hillside developments, so heating calls here range from aging furnaces to newer systems with airflow or control quirks.
Because the valley traps damp air, Bothell heating systems work through long stretches of cold, wet weather rather than short deep freezes. Filters clog faster in these conditions, and furnaces that short-cycle through damp months tend to develop ignition and sensor issues. Regular filter changes do more good here than most homeowners expect.
Heat pump repair questions
Why is my heat pump blowing cold air in heat mode?
The reversing valve may be stuck, refrigerant may be low, or the system may be locked in a defrost or cooling state. Check the thermostat mode and filter first, then call — this one needs gauges to diagnose.
Is ice on the outdoor unit normal?
Light frost that melts off during defrost cycles is normal in cold, damp weather. A unit encased in ice that never clears, or ice stopping the fan, is not normal and deserves a visit.
What does "aux heat" or "emergency heat" mean on my thermostat?
Auxiliary heat is electric backup that assists the heat pump in very cold weather — occasional use is normal. Emergency heat runs the backup alone and should only be switched on deliberately, such as while waiting for a repair.
My heat pump runs all the time. Is something wrong?
Heat pumps run longer, steadier cycles than furnaces, so long runtimes alone are not alarming. It is a problem if the house never reaches the setpoint or the auxiliary heat runs constantly — then call.
Do you repair ductless mini-splits too?
This page covers ducted (central) heat pumps that use your home’s ductwork. If your question is about a ductless mini-split, mention it when you call so you are connected with the right provider.
Do you service Bothell?
Yes — calls are connected with independent local HVAC providers serving Bothell and nearby communities. Availability depends on the provider and the time of year, so ask when you call.