Why Heat Pump Isnt Heating

Why Your Heat Pump Isn’t Heating (and What to Do Next)

A heat pump is one of the most efficient ways to heat a home in Charlottesville, VA and the surrounding areas. So when your heat pump isn’t heating, it can be frustrating, especially on a cold morning. The good news is that many issues have simple causes, and even when the fix requires a professional, catching the problem early can prevent bigger repairs.

Below are the most common reasons a heat pump may not be heating properly, plus homeowner-friendly troubleshooting steps and guidance on when to call Mack Morris Heating & Cooling.

How Heat Pumps Heat Your Home (Quick Refresher)

Unlike a furnace that creates heat by burning fuel, a heat pump moves heat. In heating mode, it pulls heat from outdoor air and transfers it indoors. During colder weather, the system may periodically switch into defrost mode to melt ice on the outdoor unit. That process can temporarily reduce warm airflow inside and can be mistaken for a heating failure.

Common Reasons Your Heat Pump Is Not Heating

1) Thermostat settings are incorrect

This is the simplest place to start. If the thermostat is set incorrectly, your heat pump may blow cool air or not run long enough to warm the house.

• Check the mode: Confirm the thermostat is set to HEAT, not COOL or OFF.
• Check the setpoint: Raise the temperature 2 to 3 degrees above room temperature and listen for the system to start.
• Fan setting: Set the fan to AUTO. If it is set to ON, you may feel unheated air between heating cycles.
• Battery power: If your thermostat uses batteries, replace them.

If you have a heat pump thermostat with Emergency Heat or Aux Heat, use those settings only as needed. Emergency Heat is typically for when the outdoor unit is not working and can increase energy costs.

2) The outdoor unit is iced over or blocked

In Charlottesville winters, it is normal to see some frost. However, heavy ice buildup can prevent proper heat transfer and reduce heating capacity.

• Look for airflow obstructions: Clear leaves, branches, and debris at least 2 feet around the unit.
• Snow or mulch drifts: Make sure the coil is not buried or clogged.
• Ice sheets: If you see thick ice that does not melt after a defrost cycle, the system may have a defrost problem, airflow issue, or low refrigerant.

Important: Do not chip ice off with sharp objects. This can damage the coil. If the unit is encased in ice, turn the system off and call for heat pump repair.

3) Dirty air filter or blocked indoor airflow

A clogged air filter is one of the most common causes of a heat pump not heating effectively. Restricted airflow can make your home feel cold, cause longer run times, and even contribute to coil freezing.

• Replace the filter if it looks dirty. Most homes need a new filter every 1 to 3 months.
• Check supply vents and return grilles. Make sure they are open and not blocked by furniture or rugs.
• If you have multiple returns, ensure they are not covered or closed.

If replacing the filter improves airflow but the heat still feels weak, the issue may be deeper, such as duct leakage, blower problems, or system sizing.

4) Aux heat is not working (or is running too much)

Many heat pumps rely on auxiliary heat (often electric heat strips) when outdoor temperatures drop or when the system needs extra help. If your aux heat is not working, your heat pump may struggle to keep up and the house may never reach set temperature.

On the other hand, if the aux heat runs constantly, you may see higher energy bills and still feel uncomfortable if the underlying issue is low refrigerant, airflow problems, or a failing outdoor unit.

Signs you may need service:

• The thermostat frequently displays AUX or EM HEAT
• Indoor air is lukewarm for long periods
• Electric bills increase suddenly

5) Refrigerant issues (low charge or leak)

Refrigerant is what allows a heat pump to move heat effectively. If your heat pump is low on refrigerant due to a leak, you may notice:

• Weak heating and long run times
• Indoor coil frosting or outdoor unit icing beyond normal
• Hissing or bubbling sounds near the equipment

Refrigerant problems require professional diagnosis. Adding refrigerant without fixing the leak is not a lasting solution. A trained technician will locate the leak, repair it when possible, and charge the system to manufacturer specifications.

6) The system is in defrost mode (normal operation)

Heat pumps periodically enter defrost mode to remove frost from the outdoor coil. During defrost, the system temporarily reverses operation and may blow cooler air inside. You might also see steam rising from the outdoor unit, which is usually normal.

Defrost mode should be brief. If it happens very frequently, lasts too long, or the outdoor unit remains iced up afterward, a defrost control, sensor, or airflow issue may be present.

7) Electrical or control issues

A tripped breaker, blown fuse, or failed capacitor can stop the outdoor unit from running, which often leads to “heat pump running but not heating.” In some cases, the indoor blower runs while the outdoor unit does not, and the air coming from vents feels cool.

• Check the breakers for both the air handler and the outdoor unit.
• If a breaker trips again after resetting, stop and call a professional. Repeated tripping can indicate a dangerous electrical problem.

8) Ductwork leaks or insulation problems

Sometimes the heat pump is working, but the warm air is not reaching your living spaces efficiently. Leaky ducts in an attic or crawl space can waste a significant portion of the heat you are paying for.

Clues include:

• Some rooms are much colder than others
• Little airflow from certain vents
• Dusty registers or musty odors from duct runs

Sealing and insulating ducts, and improving airflow balance, can make a noticeable difference in comfort and energy use.

Quick Troubleshooting Checklist for Homeowners

If your heat pump isn’t heating, try these steps before scheduling service:

1. Set thermostat to HEAT, raise temperature 2 to 3 degrees, fan on AUTO.
2. Replace the air filter.
3. Confirm all supply vents and returns are open and unobstructed.
4. Clear debris around the outdoor unit and make sure it can breathe.
5. Check breakers for the indoor and outdoor equipment.
6. Wait 10 to 15 minutes to see if the system recovers from a defrost cycle.

If you still have cold air or the home will not reach set temperature, it is time for professional heat pump service.

When to Call Mack Morris Heating & Cooling

Some heat pump problems should not be DIY. Call for heat pump repair in Charlottesville, VA if you notice:

• Thick ice buildup on the outdoor unit
• Burning smells, buzzing, or electrical issues
• The outdoor unit is not running but the indoor fan is
• Repeated breaker trips
• Aux heat running constantly or not working at all
• Signs of refrigerant leaks or persistent poor heating

Our technicians can pinpoint the root cause quickly, whether it is a refrigerant issue, a defrost problem, a failing component, or an airflow or ductwork concern. We service homeowners throughout Charlottesville and nearby communities, helping you restore safe, reliable comfort.

How to Prevent “Heat Pump Not Heating” Issues

Preventive maintenance goes a long way in keeping your heat pump efficient and dependable through Virginia winters.

• Change filters regularly: Set a reminder every 30 to 90 days.
• Keep the outdoor unit clear: Remove leaves and trim plants back.
• Schedule professional maintenance: A tune-up helps catch refrigerant, electrical, and airflow issues early.
• Use smart thermostat settings: Avoid large temperature setbacks that force heavy auxiliary heat use.

Get Heat Pump Help in Charlottesville, VA

If your heat pump is not heating, you do not have to guess. Mack Morris Heating & Cooling is here to help you get comfortable again with prompt, professional heat pump service. Whether you need a minor repair, a system adjustment, or help improving airflow and efficiency, our team will guide you to the right solution for your home.

Need help now? Contact Mack Morris Heating & Cooling to schedule heat pump repair in Charlottesville, VA and the surrounding areas.