Unless your refrigerator is so outdated or inefficient that you've already chosen to replace it with a new energy efficient refrigerator, it's a good idea to do a simple test to see if the fridge is running well. Things like how often and for how long the motor is on, whether there's frost in the freezer section, how good your door gaskets are, and the temperature of the freezer and refrigerator compartments, can all affect your fridge electricity use.

Begin by simply noticing how frequently you hear the motor churning. Does it seem to be going continuously, or is the fridge for the most part silent? Does the compressor appear to keep switching on and off (short periods of activity followed by short rests)? When the fridge door stays shut (for example overnight), the behavior of energy consumption for energy saving refrigerators is usually that of short periods with the compressor motor running, interspersed with much longer periods of the motor switched off. If that's how your fridge operates, you're in good shape.

If the motor is going continuously, there could be problems with the seal of the door gaskets, or cobwebs on the coils, or the fridge may be in a closed-in area so that the heat the motor is working to extract from the interior has nowhere to go. You may just have an old refrigerator with an inefficient compressor motor, which means less heat is extracted for a given energy input, or you might have substandard insulation in the fridge walls, so that more heat leaks in through the fridge sides. Or you might have set the temperature too low in either the fridge or the freezer compartment.

Next look for frost build-up in the freezer compartment. Rapid or heavy ice build-up in a manual-defrost freezer is usually an indication that warm, moist air is getting into the freezer compartment. You may have a bad seal on the freezer section, which allows cold air to escape through the seal, and warm, humid air to take its place. It takes more electricity to extract heat from moist air than from dry air, so you win on two fronts by minimizing air leakage. Even if you have a great seal, you should defrost a manual-defrost freezer frequently. Do not let more than a quarter inch of frost build up on the compartment walls, as it makes the compressor motor use more electricity.

Check your fridge and freezer section gaskets to make sure you have a good seal. The usual test is the dollar-bill check. Open the fridge or freezer door enough that you can slide a dollar bill halfway in, then close the door. If the bill stays tightly in place, the seal is fine in that part of the gasket. Do the same at several other points along the gasket. If at any point the bill falls out, or moves freely, try moving the bill along the seal up and down until it sticks. That will give you an idea of how big each leak might be.

You can occasionally solve gasket leaks by cleaning the gasket to take off any bits of food residue that could be preventing a good seal. But if there are gaps and the gasket is clean, you really should replace the seal.

Your refrigerator may pass the dollar bill test even though air is getting in - if the gasket is ripped. Cracks can develop in the thin part of the gasket where it attaches to the door. So run your finger along the gasket feeling for breaks, all the way around each door.

If you are a do-it-yourselfer, gaskets can be fairly easy to replace. I bought a new gasket for my refrigerator five years back and with no prior instruction had it on the door within a half hour. And an appliance repair person can install one even quicker, especially if you tell them to bring along a replacement gasket with them when you call them. So if your gasket is leaking or torn or too rigid to provide a good seal, get a new one.

What are the proper temperatures for your refrigerator and freezer sections?

The last item to look into in your do-it-yourself fridge assessment is the temperature inside both compartments of your fridge. You can use either a simple glass thermometer or an electronic probe thermometer to do this. Place the thermometer (or the probe portion, for an electronic unit) in a jar half-filled with liquid (a pickle jar works well), and leave it in the compartment for a full 24 hours. (Make sure the jar is only half full for the freezer compartment, because otherwise you'll break the jar. Avoid opening the unit for at least an hour before you do your 24-hour measurement. Check the temperature of the water in the jar. For the refrigerator section, you should strive for 39F or 40F (or 4C). For the freezer section, go for 5F (or -15C). If the refrigerator or freezer temperature is lower than this, you are wasting electricity cooling your food more than you need to.

Note that for chest or upright freezers, where food is usually kept longer than in the freezer compartment of refrigerators, you want a somewhat lower freezer temperature of 0F or -17C.

If the compartment is not at the correct setting, adjust the thermostat in the appropriate section up or down by just a small amount. Then wait another 24 hours and take another reading. It's best to adjust a little at a time, until you reach the ideal fridge temperature. Once you get to the correct setting, you can use a permanent marker to mark the thermostat dial, so you have a reference point. It's not a given that this will always give you the ideal temperature (thermostats can be finicky) but if you subsequently notice that the mark is far from its original position, you'll know to measure the compartment temperature once more.

It's important to check your fridge temperature (both compartments) regularly, or at least, if you have already checked it and have marked the correct position of the dial, to see that the dial hasn't moved. It's easy for these dials to get turned inadvertently, or on purpose by little hands, and if the temperature varies far from the proper settings of 40F for the refrigerator compartment or 5F for the freezer section, you either risk food spoilage or a higher energy bill.