What should I do if my heat pump outdoor unit is not running?

What this symptom usually means

When the heat pump outdoor unit is not running, the problem is usually in the power supply, start components, contactor, or controls for the outdoor section itself. This symptom is different from weak heating or cooling: the key clue is that the outside cabinet stays still and quiet, or only clicks or hums, when the thermostat is clearly calling. In many homes, the indoor blower may still run while the outdoor unit does nothing, which often points to a breaker, disconnect, capacitor, contactor, or low-voltage control issue rather than an airflow problem.

How to narrow it down by what you can observe

A completely silent outdoor unit often means it is not getting power or not receiving the call to run. If the thermostat appears normal but the outdoor section shows no fan movement, no compressor sound, and no vibration at all, a tripped breaker, blown fuse, pulled disconnect, bad contactor, or low-voltage fault moves to the top of the list. If you hear a click, brief hum, or repeated start attempts, that more often fits a failed capacitor, a tight or failing compressor, or a fan motor that cannot get up to speed. If the thermostat or air-handler display shows a code or alert, the system may be in lockout and intentionally preventing the outdoor unit from starting until the underlying fault is diagnosed.

What not to do while you wait

Do not keep lowering or raising the thermostat to force repeated restart attempts. That can overheat a struggling compressor, repeatedly trip breakers, and make an intermittent electrical fault harder to trace. If a breaker has clearly tripped once, one reset may be reasonable; if it trips again, leave it off and arrange service, because repeated trips usually mean a real electrical or mechanical problem in the outdoor unit.

What a technician usually checks on this call

A service visit for an outdoor unit that will not run typically starts with confirming the call for heating or cooling, then checking incoming high voltage, the disconnect, breaker status, and low-voltage signal to the contactor. The technician will usually test the dual run capacitor, inspect the contactor for burned contacts, read any fault codes, and verify whether the fan motor and compressor are drawing normal amperage. If the system uses communicating controls, they may also check board-to-board communication and sensors before deciding whether the outdoor section is locked out for protection.

What affects repair cost

Cost depends heavily on whether the issue is external electrical supply, a small replaceable component, or a major motor/compressor failure. In many markets in 2025-2026, replacing a capacitor or contactor is often in the low hundreds of dollars, while diagnosing and repairing wiring, board, or sensor issues can vary more because of labor time and brand-specific parts. A condenser fan motor repair is usually more than a capacitor job, and compressor replacement can run into the thousands and sometimes pushes the conversation toward full equipment replacement, especially on older heat pumps or units using expensive proprietary parts.