Heat Pump Not Heating? What's Normal, What's Not, and 5 Checks
Heat pumps confuse people, because a working heat pump doesn't feel like a furnace. Before you call anyone, it helps to know what "normal" is — then run five checks.
Safety first: if you smell gas anywhere in the house, leave and call your gas company from outside. Heat pumps don't burn gas, but a gas furnace or water heater nearby might.
What's normal (and often mistaken for broken)
- The air feels lukewarm, not hot. A heat pump moves heat instead of making it. Air from the vents is often 85–95°F — warm to a thermometer, cool to a hand that expected furnace heat. If the house holds temperature, it's working.
- Steam or a puddle at the outdoor unit in winter. That's the defrost cycle melting frost off the coil. Normal, a few minutes at a time.
- It runs a long time. Heat pumps are designed to run long and steady, not blast and stop.
Now the checks.
1. Thermostat mode and setpoint
Mode on HEAT (not AUTO on some models, not EM HEAT unless you mean it). Setpoint a few degrees above the room. If the screen is dim or blank, fresh batteries.
About "EM HEAT" / "Emergency heat": that switches you to backup electric strips — expensive to run. Only use it if the heat pump has actually failed. If someone set it and forgot, your bill goes up and the heat pump sits idle.
2. Two breakers
Heat pump systems usually have two breakers: one for the indoor air handler and one for the outdoor unit. Check both. Reset a tripped one exactly once — fully OFF, then ON. If it trips again, stop; that's a real fault.
3. The filter
A clogged filter starves airflow; the system can't move heat and may shut itself down. Hold the filter to the light. Can't see through it? Replace it.
4. The outdoor unit
Is the fan on top spinning? Is the unit buried in snow, leaves, or ice? Clear it (power off first — the breaker or the shutoff box on the wall next to it). Keep 2 feet clear around it and don't let snow bury the sides.
If the outdoor unit is a solid block of ice — not frost, ice — turn the system off and let it thaw. A frozen coil can't work and running it makes it worse.
5. Vents and registers
Walk the house. Every supply vent open? Nothing pushed up against a return? A closed-off room or a blocked return is a common "no heat" that isn't.
When it's a pro
If the outdoor unit hums but the fan never spins, if the breaker keeps tripping, if the air is cold (not lukewarm) with the outdoor fan running, or if EM HEAT is the only thing that warms the house — that's a capacitor, reversing valve, or refrigerant issue. Technician territory.
Before you call, run the free troubleshooter. It rules the simple stuff out on the record and hands you a summary the tech can actually use.
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