Heat Pump Not Heating: Safe Checks and When to Call
A heat pump that blows cool air or won't heat the house is frustrating, and the cause is often simple. This guide covers the common reasons, what is normal in cold weather, safe checks to run first and when to call a professional. LocalRepairLine is a referral service, not a contractor, and this is general information, not a substitute for an in-person inspection.
Safety first
If you smell gas, burning plastic or see smoke, turn the system off and leave the area. Don't chip ice off the outdoor unit with tools, because the coils are fragile. Don't remove panels from the outdoor or indoor unit while it's powered. Refrigerant and electrical work must be done by a professional.
Why a heat pump may not heat
- Thermostat settings. The system may be set to cool, off, or emergency heat, or the batteries may be low.
- A dirty air filter. It restricts airflow, so the system struggles to deliver heat.
- Ice on the outdoor unit. Light frost that melts during a defrost cycle is normal. Thick ice that stays isn't.
- A blocked outdoor unit. Leaves, snow or debris around it reduce airflow.
- A tripped breaker or a failed part. Contactors, capacitors, fan motors or the reversing valve can fail.
- Low refrigerant. This is a leak problem that a professional must find and repair.
Safe checks to run first
- Set the thermostat to Heat and raise the setting a few degrees above room temperature. Replace the batteries if the display is weak.
- Check the filter. Replace it if it looks clogged.
- Check the breakers for both the indoor and outdoor units. Reset a tripped breaker once.
- Look at the outdoor unit. Clear loose leaves and snow from around it, keeping a gap of a couple of feet. Check that the fan is turning when the system runs.
- Look for ice. A thin layer that clears during a defrost cycle (you may see steam) is normal. A thick block or ice on the pipes is a sign of a problem.
- Check the vents. Make sure indoor registers are open and not blocked.
- Feel the air. A heat pump often delivers air that feels milder than a furnace, which is normal, but it should still warm the home over time.
What not to do
- Do not run emergency heat all winter without checking why the heat pump isn't working.
- Do not hit or chip ice off the unit.
- Do not cover the outdoor unit with a tarp while it runs.
- Do not keep resetting a breaker that trips again.
- Do not add refrigerant yourself.
When to call an HVAC professional
- Thick ice stays on the outdoor unit or the lines.
- The outdoor fan or compressor doesn't run, or you hear grinding or loud banging.
- The system runs constantly but the house doesn't warm up.
- Auxiliary or emergency heat runs all the time.
- You smell burning, or a breaker keeps tripping.
What to tell the technician
- The make and approximate age of the system, if you can see the label.
- What the thermostat is set to and whether emergency heat is on.
- Whether the outdoor fan runs and if there's ice.
- What you checked: thermostat, filter, breakers, outdoor unit.
Still no heat?
If you worked through the list and the heat is still not working, describe the problem to an independent local contractor. A short automated prompt plays first, and then you're connected. LocalRepairLine is a referral service, not a contractor.
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