What should I do if my heat pump runs constantly or will not turn off?

What constant heat pump operation usually means

A heat pump that runs constantly is usually not simply “working hard.” In most homes, it should cycle off after it reaches the thermostat setting, even if run times are longer during very hot or very cold weather. When it keeps operating without catching up, the system is either struggling to transfer heat, being told to keep part of the system running, or failing to complete a normal operating sequence such as defrost.

How to tell which version of this symptom you have

Start by noticing whether the outdoor unit and indoor unit both keep running, or whether only the indoor fan continues after the heating or cooling ends. If room comfort improves slowly while the system runs, airflow problems, low refrigerant, or performance loss at the outdoor unit are common suspects. If comfort does not improve at all, the problem is usually more serious, such as a sealed-system issue, outdoor component failure, or a control problem. If you see ice, water around the unit from repeated thawing, or hot electrical smells from overheating components, the nonstop operation is often a side effect of the system fighting another fault.

Clues homeowners can observe without opening equipment

A blower-only problem often shows up as air still coming from the vents after the heating or cooling sound stops outside; that points toward the fan being commanded on or a relay stuck closed. If the outdoor unit is frosted over in heating mode and the heat pump never seems to recover, a defrost failure moves higher on the list. If some rooms have weak airflow, the indoor coil can get too cold or too hot because not enough air is moving across it, which extends run time dramatically. If the thermostat remains several degrees away from the setpoint for hours, low refrigerant or a compressor-side performance issue becomes more likely than a simple fan setting issue.

What a technician typically checks on a service visit

A technician will usually verify whether the thermostat is correctly calling for heating, cooling, or fan only, then measure temperature split, airflow, and amp draw to see whether the system is moving heat normally. They may inspect the indoor coil and blower, check whether the outdoor fan and compressor are both operating, and test defrost controls and sensors if icing is involved. If the readings suggest a sealed-system problem, they will check operating pressures and look for signs of refrigerant loss or poor compressor performance rather than just assuming the long run time is weather-related.

What affects repair cost for a heat pump that will not shut off

Cost depends on whether the system is running nonstop because of a control issue, an airflow problem, or a refrigeration/performance fault. Thermostat replacement or fan relay/control repairs often land around $150-$600, while blower motor or capacitor-related repairs are commonly higher depending on equipment type. Defrost board or sensor repairs often fall in the mid-hundreds, and refrigerant leak diagnosis and sealed-system repairs can range from several hundred dollars into the thousands once leak repair, refrigerant, and component replacement are involved. Older systems with repeated icing, poor capacity, or compressor wear can make replacement discussions more likely than a minor repair.