October 28, 2024
The Bay Area might not be known for harsh winters, but high humidity and sudden temperature drops cause your heat pump to ice up when you need it most. While some frost is expected, it’s important to know when heat pump freezing becomes excessive and requires further attention.
Heat pumps extract heat from the outdoor air to warm your home during the winter. This heat transfer process drops the surface temperature of the condenser coils, causing the increased moisture in the air to freeze on the coil’s surface.
Minor freezing is expected and most heat pumps have a built-in defrost cycle to melt the ice that has accumulated on the compressor unit. When the heat pump sensor detects cold temperatures, it switches to air conditioning mode and directs warm air outside until the coils reach an appropriate temperature, then switches back to heating mode.
Certain conditions may disrupt this process and result in a malfunctioning heat pump defrost mode and excessive ice buildup. Heat pumps are complex systems with many moving parts — when one or more parts fail, the pump can’t work as efficiently and may be more prone to icing. Common causes of ice buildup include:
Extreme weather: Severely cold temperatures may impede the defrost cycle’s effectiveness, particularly in moisture-prone areas.
Faulty defrost sensor: When a heat pump strains to cool your home in severe conditions, the defrost sensors and control board overheat and fail.
Reversing valve failure: The reversing valve changes the direction of heat exchange — if it fails, your system can’t direct warm air outside to defrost.
Compressor problems: Many factors can limit compressor performance, disrupting the heat exchange and defrosting process.
Restricted airflow: Blocked vents or clogged air filters hinder airflow, causing the system to overwork and potentially freeze.
Low refrigerant: Whether due to insufficient charging or leaks, low refrigerant prevents your heat pump from absorbing heat as efficiently.
Some frost or ice on your heat pump is normal, but other signs suggest more significant problems. These include:
Persistent freezing and ice buildup on the outdoor unit
Frozen evaporator coil
Heat pump isn’t heating or running
Strange noises
Insufficient or no airflow from vents
High energy bills
Try these troubleshooting steps if you suspect your heat pump is frozen.
Ensure the area surrounding the heat pump is clear of leaves, dirt, and other debris that obstructs airflow. Check for gutters or tree branches leaking water from above or pooling water around the compressor.
Dirty air filters restrict airflow and eventually clog, making the heat pump work harder and increasing the likelihood of freezing. Replace the air filter with a compatible model as per your owner’s manual.
Your heat pump may not activate defrosting mode automatically if a faulty sensor or incorrect thermometer programming doesn’t allow it to detect cold temperatures or ice. Check that your thermostat is properly programmed. If defrost mode doesn’t switch on within a few minutes, consult the user manual for manual activation instructions. If the manual defrost works, the sensors are likely faulty.
Dust and debris accumulate on the evaporator coil over time, preventing optimal heat transfer if left dirty. Evaporator coils are delicate — leave cleaning dirty coils to an HVAC technician to avoid damage.
Proactive measures reduce the risk of freezing over during the winter and improve your heat pump’s overall performance.
While certain tasks are straightforward, many heating and cooling concerns require attention from a certified HVAC technician. Attempting certain repairs on your own may be hazardous and cause further damage to your system, so calling a professional is often a more cost-effective strategy. A professional can help with:
Complex repairs: Certified HVAC technicians are trained and experienced in diagnosing problems with complex heat pumps. They safely handle refrigerant leaks, motor breakdowns, and other underlying problems contributing to freezing.
Choosing the right heat pump: Some heat pumps aren’t engineered for optimal performance at severely cold temperatures. Even in Northern California, high winter humidity combined with occasional cold snaps often encourages ice buildup. Heat pumps rated for cold climates work efficiently in temperatures as low as -15 degrees, offering enhanced freeze-resistance reliability over standard models.
Ensuring proper installation: To optimize efficiency and reduce the risk of ice buildup, your HVAC technician should carefully consider your home and its needs to appropriately size and install your heat pump. Outdoor units also typically need a level pad made from concrete or other sturdy materials to keep them above the ground and minimize exposure to rain, sleet, and groundwater.
Aside from professional repairs, periodic DIY maintenance helps keep your system running smoothly. Try these maintenance tips:
Replace air filters every three months or sooner
Inspect ductwork for leaks and damage
Ensure vents are open and unobstructed
Keep the compressor clear of debris
Schedule professional maintenance at least once per year
Keep your home comfortable throughout winter with maintenance and repair strategies from Service Champions. With expert HVAC technicians, flexible financing, and a 100% money-back guarantee, you can enjoy dependable heat pump performance in mild temperatures and cold snaps alike. Contact us or book online for a service.
Although covering your heat pump technically protects it from snow, ice, and other debris or exposure, directly covering it prevents proper operation, reduces airflow, and encourages moisture buildup.
Excessive and persistent ice buildup on your heat pump reduces efficiency, leading to high energy bills, poor heating, and excessive mechanical stress. In some cases, this mechanical stress can lead to damaged components or a system failure.