Why Isn’t My Payne Heat Pump Defrosting?

Due to their ability to self-defrost, heat pump systems can experience temporary freeze-ups. Only when a heat pump freezes for longer than four hours and doesn't appear to be successfully defrosting itself do serious problems arise. Here is what we learned after researching why Payne heat pumps don't defrost.

The following is a summary of the reasons why your Payne heat pump isn't defrosting:

  • Outside unit is obstructed
  • Outside fan issues
  • Low refrigerant
  • Defrost timer not working properly
  • Obstructed filters
  • Dirty coils

The defrost system on your heat pump often has a timer that needs the compressor to run for a predetermined amount of time before it begins a defrost cycle. A defrost sensor that is connected to the defrost system informs it that the coil has frosted over. For more information, keep reading.

Two air source heat pumps installed on the exterior of a modern house, Why Isn't My Payne Heat Pump Defrosting?

Reasons A Heat Pump Doesn't Defrost

When icing occurs regularly, a Payne heat pump must frequently defrost. The defrost mode runs for a brief length of time and is effective enough to melt the ice without wasting energy or time on heating the house. The causes of your Payne heat pump not defrosting are listed below.

Reasons A Heat Pump Doesn't Defrost - Central Air Conditioner frozen or iced up heat pump

Outside Unit Is Obstructed

Winter snowdrifts can prevent the ice on your outside unit from thawing if they have built up around it. The diminished airflow may result in even more ice accumulation. 

You should regularly clear the snow from the area around the exterior unit. Never use a sharp object to chisel away at the ice while it is defrosting.

Outside Fan Issues

The fan in your outdoor unit circulates air over the coil that contains the refrigerant, which is necessary for the heat transfer process needed to heat or cool your home.

If your outside fan is broken, there won't be much airflow, and this can lead to your outdoor unit freezing over. In this situation, have your outdoor fan motor examined by a specialist.

Low Refrigerant

Since refrigerant is essential for heat transfer, a refrigerant leak will result in insufficient heat transfer. Your heat pump will eventually run out of heat before the ice on the outer unit melts. Never try to fix a refrigerant leak yourself if you suspect one; always call a professional.

Your heat pump's numerous parts will experience increased stress as a result of low refrigerant. Low refrigerant levels may be to blame if you observe a big increase in electrical expenses. A refrigerant leak can result in a multitude of problems for a heat pump.

Defrost Timer

Another potential issue with your appliance is a broken defrost timer. Your heat pump's defrost mode is intended to periodically activate. Your unit is not defrosting as regularly as it should, which causes ice buildup if your defrost timer is broken.

Your heat pump will occasionally switch to air conditioning mode in the winter to thaw the ice on the outdoor unit. The exterior unit is heated when in air conditioning mode, melting any frost or ice. Ice can accumulate quickly if the appliance is not defrosting.

Obstructed Filters

Dirty filters restrict airflow, and the coils will freeze over if there isn't enough air flowing through them. When the coils freeze over, they are unable to heat or cool correctly, which leads to an accumulation of ice on the exterior unit.

Dirty Coils

Effective heat transfer between the coils and the outside air is impossible if the coils are dirty and covered with grease or grime. A film of ice develops on the coils as a result of the refrigerant inside them being too cold when the coils are unable to transfer heat to the air.

Your heat pump cannot effectively heat or cool as a result. Additionally, it can't effectively thaw the outer unit. As a result, the external unit's icing gets worse.

How Do You Deal With A Frozen Heat Pump In The Winter?

Winter weather can cause heat pumps to ice up, and in some cases, light ice or white frost covering the coil as a whole is expected. It is rare for the entire unit, including the top and the inside of the coil, to stay totally coated with ice for long. Here are a few solutions to this problem:

  • Observe the system for a while
  • Start the fan
  • Manually start the defrost cycle
  • Move detector

Iced heat pumps signal a problem and should be handled quickly to conserve energy and avoid significant damage to the equipment. Different heat pumps use various methods to decide when to enter defrost. Let’s elaborate on the list of potential causes and solutions.

How Do You Deal With A Frozen Heat Pump In The Winter - The outdoor unit of an air-source heat pump after a winter storm.

Symptoms of The Problem

It's not normal for the entire unit, including the top and inner coil, to be covered with ice for an extended period.

The condensing fan motor must be able to pull air in and out via the unit's fins for proper operation. If it is unable to do this, your unit is not performing at its highest capacity and has a problem. Here are a few approaches to this question.


Your heat pump's defrosting system, especially if it's more modern, probably doesn't have any problems and is currently working diligently to thaw your system and get it back up and running.

Sometimes the defrost mechanism only needs a little more time to work, which can give the impression that there is an issue when there isn't.

Start The Fan

To try to defrost it, just turn on the fan. Set the fan to the exhaust setting if the outside temperature is extremely chilly. Although running the fan for a while might not completely resolve all troubles and freezing issues, it is a temporary fix you can try.

If the fan is broken or completely dead, it can prevent the unit from releasing heat and lead to ice buildup.

Defrost Cycle

Activating the defrost cycle manually is an additional option. The outdoor fan is turned off and the outdoor evaporator is transformed into a condenser when the defrost cycle is activated by flipping the valve to air conditioning mode.

Defrost Cycle - The outdoor unit of the air conditioner (air-to-air heat pump) in the snow during winter operation.

A heat pump occasionally goes through a defrost cycle to avoid the accumulation of frost. In essence, this redirects all of the heat that is being transferred within your home outside through the condenser coils, melting the ice that has formed around the unit.

Move Sensor

Moving the temperature sensor on the heat pump unit's exterior is the final remedy you might try on your own.

When there is frost, your heat pump needs to operate harder to melt the ice. The defrost cycle might not run long enough if the sensor is exposed to direct sunlight or is otherwise warmer than the rest of the device.

See this Payne heat pump defrost sensor on Amazon.

Can I Defrost My Heat Pump With Hot Water?

One of the best ways to thaw a frozen heat pump is to pour hot water on it. Your heat pump will work more efficiently as the ice is removed by the hot water. Attempting to melt the ice is a good course of action. If you try to manually break it apart, you can harm the pump.

The coils or refrigerant pipes may start to produce ice as the temperature gets close to freezing. A defrost cycle can be offered for your heat pump model to combat sudden cold spells. Continue reading as we go deeper into this issue.

Can I Defrost My Heat Pump With Hot Water - Jet of water spraying from garden hose pipe

Why Is It Okay To Pour Hot Water On A Frozen Heat Pump?

Physically removing the ice from the pump could damage some of its more sensitive parts, so we advise against manually breaking up the ice. Your pump could be destroyed by this in a single action. Here’s how to use hot water to thaw a frozen heat pump.

Determine The Water’s Temperature

Determine The Water’s Temperature - water and basin

Placing your finger in it will allow you to determine if it is hot enough to cause the ice to melt. You can proceed if the item is steaming, somewhat burns, and would be suitable for soup.

You don't have to be concerned about the pump being burned by the water's warmth because heat pumps are designed to operate with heat.

Use A Hose

Use Hose - green hose from which flows a stream of clean water

To remove any snow and ice, you can pour hot or warm water over your heat pump. You can even use cold water from a hose in some mildly cold areas.

Check out this hose on Amazon.

In Closing

There are several reasons why your Payne heat pump may fail to defrost. A number of factors may be preventing heat from transferring as it should, such as a refrigerant leak, a blocked filter, or dirty coils.

Contact a specialist for help if you need to shut the system down to stop further damage.

If you find this article informative, check out these related articles:

How To Tell If Your Heat Pump Has Auxiliary Heat

Heat Pump Efficiency Vs. Temperature – How Do The Two Relate?

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