The How Zone

Fix A Fridge

How a fridge should work

Our refrigerator started acting up one day after a power outage: cold on one side (freezer), hot on the other (fridge). Even though it is only a few years old the warranty only covered big items, like the compressor. But how do you tell what's broken without potentially spending money on a repair call? Here's what I found and how it was fixed.

First off, before we dive into our particular refrigerator problem, let's review how a basic refrigerator works. At the very heart a fridge is a heat pump that removes, or "pumps" heat out of a closed space (the inside of your refrigerator) and transfers it into the air surrounding it. In other words it heats your house and in turn cools the inside of the fridge.

Let's think of heat as a bunch of energetic molecules bouncing around like puppies in a cardboard box. If you have a great big box the puppies still bounce around but it takes longer to get from one side to the other. Put the same number of hyper pups into a small box and they seem to be really flying about, ready to tear the box apart. Same energy, but the density of energy is higher.

AC Diagram

A fridge uses a compressor to take a bunch of hot gas, something like freon, and compress it. This not only squeezes all of that heat energy into a smaller space but also liquifies it. The hot, pressurized liquid is run through a series of heat coils, a radiator, (under or behind the fridge) with a fan that blows air across the coils to remove heat. When someone says "be sure to clean your fridge coils" they are talking about these coils.

Dust bunnies are a refrigerator's only natural enemy.

After removing as much heat as we can the liquid goes through an expansion valve for the evaporation stage. It emerges from the other side of the expansion as a low temperature, low pressure liquid which goes through coils inside the fridge, often called the evaporator. Any heat (the term is relative of course) in the refrigerator causes the liquid to boil and turn into a gas again, absorbing heat in the process.

The gas goes back to the compressor and the whole process starts again.

Oddly enough you can refrigerate using fire, like they use in propane fridge

   Page 1 of 6 Freezer vs. Fridge»