demand defrost mode

Heat Pumps

Heat Pump Too Frosty? Some Tips For Keeping It Ice-Free


It doesn’t take a snow storm to cause the heat pump condenser coil to ice over. Something as simple as a clogged air filter could be to blame. If you have problems with your coil accumulating ice, read through these causes for ice accumulation, and some troubleshooting tips to remedy the problem before you call in the pros. In heating mode, the refrigerant inside the outdoor condenser coil becomes extremely cold, while the refrigerant inside the indoor evaporator coil becomes extremely hot. This is heat exchange, and it’s the process that gives heat pumps up to 400 percent heating efficiency.However, when there is a glitch in the components which overburdens the system, efficiency and performance drop drastically, and the condenser coil ices over. These are some of the common issues for ice accumulation:

  • Airflow is blocked or hindered by a clogged air filter, dirty condenser coil, malfunctioning air handler, and snow and/or other debris blocking airflow at the outside cabinet.

  • Refrigerant charge is too high or low.

  • Demand defrost mode isn’t functioning properly (bad timer, sensor or relay).

  • Thermostat is faulty.

  • Electrical contacts are worn.

  • Air handler is malfunctioning or broken.

Except for specific electrical issues, or demand defrost malfunctions, all of these heat pump issues cause ice accumulation on the condenser coil by exerting too much stress on the system. Check all possible issues with hindered or blocked airflow. Ensure the outside cabinet has two or more feet of clearance on all sides. Check to see if the air handler is working.Significant issues, such as those involving faulty electrical components, thermostat or demand defrost malfunction, a sticky reversing valve or air handler issues, should be serviced by an HVAC professional. If after removing airflow obstructions, your heat pump still does not defrost properly, call your HVAC pro. Do not attempt to chip the ice away, or you may risk more serious damage.If you have any questions about your heat pump, or if you would like to schedule a service call, contact us at Air Assurance today. We proudly serve homeowners of the Greater Tulsa Metropolitan Area.Our goal is to help educate our customers in the Tulsa and Broken Arrow, Oklahoma area about energy and home comfort issues (specific to HVAC systems). Image courtesy of Shutterstock