What is a Refrigerant Pump?

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  • Written By: Jeri Sullivan
  • Edited By: J.T. Gale
  • Last Modified Date: 20 November 2019
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A refrigerant pump is part of a heating, ventilating, and air conditioning (HVAC) unit. An HVAC unit is responsible for heating and cooling the interior of buildings. The unit may also filter fresh air drawn in from the outside and expel indoor air to reduce contamination levels. Other refrigeration equipment, such as refrigerators and freezers, also use a refrigerant pump.

An air conditioning system works by cooling air that is pumped inside and circulated. A refrigerant pump is part of that system. The liquid refrigerant is located in the bottom of the evaporator where it flows up and over a set of cooling coils. As the liquid flows through this cooling loop, it absorbs heat and starts to boil. Once it boils, it turns into vapor known as Freon™.

The vapor then is pulled into a piece of equipment known as a compressor via suction pressure on the inlet lines. The refrigerant pressure builds up in the compressor as the refrigerant vapor also absorbs heat from the mechanical movements inside the refrigerant pump and other moving parts. This flow of vapor becomes extremely hot which also increase the pressure inside the compressor. As the pressure builds, the compressor discharges the vapor through and outlet line which moves it to the condenser.


The condenser is able to remove the built-up heat and convert the vapor back into a liquid. It does this by blowing the hot air outside and retaining the liquid by moving it to the expansion device. The expansion device, known as a thermostatic expansion valve (TEV), regulates the temperature and pressure in which the liquid refrigerant is returned to the refrigerant pump. There is a sensor bulb within the TEV that monitors the temperature.

Using a suction line, the liquid flows back into the refrigerant pump to start the process again. The refrigerant pump then pushes the liquid through the evaporator. This allows cool air to blow into the indoor space using a blower fan that is attached to the back of the evaporator.

The refrigerant pump on refrigerators and freezers work in much the same manner. Coils on the back of the system pass liquid refrigerant through them, which in turn heats the liquid and turns it into vapor. A compressor builds pressure which is released through the expansion valve. The cooling turns the vapor back into a liquid and the process begins again. This continuous loop of heating and cooling is what keeps cold the food that is inside.


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Post 4

@everetra - Regardless of what is the real cause of a problem with an air conditioner, you should also have it inspected for leaks.

Let’s say that all you need is Freon. You have someone fix that problem and so you think you’re out of the woods; but six months later your AC is not pumping cool air anymore.

When you have it inspected it turns out that it’s leak in the refrigeration pump. Anytime a certified inspector checks your air conditioner he should always look for leaks. That could prevent worse problems down the road.

Post 3

@nony - I second that motion. I had a problem with my AC once. I lived with it for awhile, enduring the blistering summer heat by just pulling down the windows on my car.

I didn’t want to go to the mechanic because I was afraid of what I would find. Finally, when I could stand the heat no longer, I went to have the car checked, hoping that it was just Freon or a liquid that needed to be added.

I had no such luck. It was the air conditioning pump and it cost me a lot of money to replace it. Did I need cool air that bad? In hindsight, maybe no; but I went ahead and did it anyway.

Post 2

That’s an interesting – and concise – explanation. I had always thought that the term “Freon” referred to the liquid that is moved over the cooling coils; I didn’t realize that it was the actual vapor itself.

People often talk about adding Freon to your air conditioner in your car and in my mind I picture liquid being added. At any rate it’s clear from the explanation that Freon is the output, but the real work is done by the compressor.

If you have anything go bad in your AC system, I say that it’s better to have a problem with the Freon or the cooling liquid rather than the compressor itself. If the compressor goes bad it’s expensive.

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