What Causes High Pressure Lockout on Heat Pumps?

If they want to save on repair costs and inconvenient breakdowns, it’s vital for heat pump owners to know how their units work. Versatile and efficient HVAC systems provide comfort in buildings across the country. However, like any other heating or cooling system, heat pumps can experience issues.

For example, one common problem that heat pumps run into is a high pressure lockout. What causes high pressure lockout on heat pumps? Below, the trusted heat pump repair experts in Hickory, NC, explain what high pressure lockout is, its common causes, and the best ways to prevent it.

You can also contact the Hickory Heating and Cooling LLC team for quick service to restore your comfort and your HVAC’s energy efficiency; we know the ins and outs of these systems. 

What Is High Pressure Lockout on Heat Pumps?

Though it can sometimes be frustrating, high pressure lockout is an essential safety feature of heat pumps. It involves a shut-off switch that monitors the pressure in the refrigerant system. If the pressure exceeds a set limit, the high pressure lockout feature shuts down the heat pump to protect the internal components.

Common Causes of High Pressure Lockout on Heat Pumps

Though it is a necessary feature, high pressure lockout can create issues that shut it down when it should be working. When this happens, it can no longer provide the warm or cool air that homes and businesses require, resulting in an uncomfortably muggy or chilly indoor environment.

So what causes high pressure lockout on heat pumps? Well, several factors may raise refrigerant pressure or falsely trigger the safety feature.

Dirty or Clogged Air Filters

Heat pumps require proper airflow to function correctly and keep refrigerant pressure levels stable. By trapping contaminants and pollutants, air filters help maintain proper static pressure, airflow, and circulation within the system.

However, an air filter will amass dirt and debris over time and can eventually become clogged. It will then restrict airflow and cause refrigerant pressure to increase to unsafe levels.

Blocked Condenser Coil

A heat pump’s condenser coil is essential, as it releases heat from the refrigerant. But an overly dirty or blocked condenser coil cannot effectively release heat. As the refrigerant becomes warmer, it builds pressure and can trigger the high pressure lockout.

Improper Amounts of Refrigerant

A heat pump requires a certain amount of refrigerant to function properly. Too much or too little refrigerant can cause pressure levels to rise and set off the high pressure lockout. 

The amount of refrigerant within a heat pump may be off for a few reasons. Firstly, a leak can let refrigerant escape, either via a crack in the heat pump or coils or tiny holes that sometimes form. When this happens, the remaining refrigerant works harder and increases system pressure. 

Other causes of improper refrigerant levels are blocked capillary tubes and malfunctioning expansion valves. Both components are responsible for regulating refrigerant flow (the capillary tube to the condensing coil and the expansion valve through the entire heat pump). If they cannot function correctly, they can cause the refrigerant levels to increase or decrease and internal system pressure to rise. 

Malfunctioning Pressure Switch

The high pressure switch is crucial, and a malfunctioning one is the most common cause of an unnecessary high pressure lockout occurrence. The switch monitors the pressure within the refrigerant and shuts down the heat pump if the pressure is too high. However, if the heat pump shuts down, it’s always possible that the pressure switch tripped the lockout for no reason. 

A malfunctioning pressure switch will often fail to shut down the heat pump, though. If the pressure is indeed high, you need this switch to do its job. Otherwise, you’ll likely have a system replacement in the near future.

How To Prevent High Pressure Lockout on a Heat Pump

Home and business owners can take a few simple steps to help prevent high pressure lockout on their heat pumps. 

• First, regularly replace air filters, about once a month, to ensure proper airflow. 
• Next, keep an eye out for leaks and other suspicious signs of improper refrigerant levels.
• Perhaps most importantly, heat pump users should schedule regular system maintenance to allow technicians to inspect and service their heat pumps.

Contact Hickory Heating and Cooling LLC Today!

Now that you know what causes high pressure lockout on heat pumps, you’ll be ready to quickly spot and address the safety feature. To book a service appointment with our experts, or to learn about heat pump electrical requirements, call Hickory Heating and Cooling LLC today at (828) 827-5224