Why Is My Heat Pump Not Heating? 6 Common Causes (and Fixes)

A heat pump that won't heat on a cold, wet Oregon morning is no fun. The good news: the cause is often simple. Here are the six most common reasons, and what to do about each.

1. It's stuck in cooling mode

It sounds obvious, but a thermostat set to "cool" (or a mode glitch) is a frequent culprit. Make sure it's set to Heat and the temperature is above the current room temp.

2. The outdoor unit is iced over

In our damp winters, a thin layer of frost is normal, your heat pump runs a defrost cycle to clear it. But if the outdoor unit is encased in ice, airflow is blocked and it can't pull in heat. Turn the system off and call a pro before running it more.

3. A clogged air filter

A dirty filter chokes airflow, so even when the system is "working," not much warm air reaches your rooms. Check and replace your filter, this is the single most common fix, and the cheapest.

4. Low refrigerant

A heat pump moves heat using refrigerant. If there's a leak, it can't move enough heat and you'll feel weak, lukewarm air. This needs a technician, see our heating & furnace repair service.

5. It's in (or stuck calling for) backup heat

In a hard freeze, many systems switch to backup/auxiliary heat. That's normal, but if it's running constantly in mild weather, something's off and your bills will spike.

6. The unit is undersized or aging

If your heat pump never quite keeps up, it may be undersized for your home, or simply worn out. If it's more than ~12–15 years old and struggling, replacement (often with Energy Trust rebates) may cost less than chasing repairs.

When to call us

Filter and thermostat checks are DIY. But ice, weak air, constant backup heat, or no heat at all are signs to call a pro before a small issue becomes a big one. Central Coast Heating & Air offers same-day service across Philomath and the surrounding area, give us a call and we'll get your home warm again.

Related service: Heat Pump & AC Installation