This post is the thirteenth in a multi part series on swamp cooler repair, maintenance, and replacement options, like refrigerated air conditioning. If you haven’t read parts 1 – 12, I recommend you do before continuing.

Elements of the refrigeration cycle (continued)

An illustration of the refrigeration cycle. Refrigerated air conditioning


The refrigeration cycle works on a basic law of physics: when liquids change state into gaseous from, they absorb heat, and when gases change state into a liquid, they give off heat. This sounds great, but how do we get the state change to happen without adding or taking away heat? Easy, we change the pressure.

When the refrigerant enters the compressor, it is a low pressure gas. The compressor itself is a simple, single piston electric motor with one way valves. When the piston strokes downwards, it draws in low pressure gaseous refrigerant. When the piston reaches its lowest point, the one way valve that let the refrigerant in closes. As the piston strokes back to its highest position, it pressurizes the refrigerant in the cylinder, and a second one way valve opens, allowing the pressurized refrigerant out into the “high side” of the loop. In refrigerated AC terminology, the “high side” describes the half of the loop where the refrigerant is under high pressure, while the “low side” describes the half of the loop where it is under low pressure.


Refrigerant enters the condenser as a high pressure gas. The condenser itself is a coil of metal tubing designed to maximize surface area. If you look at the back or bottom of your fridge, that big squiggle of tubing you see is the condenser. As the refrigerant passes through the condenser, it cools, giving off its heat to the outside air. As the temperature drops, the refrigerant changes state to a liquid because of the pressure it’s under. This is how refrigerated air conditioning systems release unwanted heat to be dissipated.

Check back soon for How to maintain your swamp cooler, when to replace it, and what to replace it with, part 14. In the meantime, check out our page on refrigerated air conditioning.