There is a natural tendency for people, especially Americans, to always opt for the biggest and best air conditioner they can possibly afford. The going thought is, the bigger the unit (as long as it fits in the window), the better it will work. It will cool the room faster, and thus use less energy.
This isn’t the case.
A professional knows what the homeowner doesn’t. In this instance, the right sized air conditioner should be selected for the room it will be placed in.
Under most circumstances, the btu, or cooling power, …

When a portable air conditioner that is in good working order senses (through a thermostat) that the temperature of the air in the room is too high, or above the threshold set, it begins the cooling cycle. Modern window unit air conditioners typically operate in “dual” phases – and cool using one of the phases. This is set at the factory to ensure the most efficient use of energy.
The first phase uses the internal fan. When the fan turns on, air is blown into the room to circulate it. The …

Before you plug in the AC and crank it up, there’s some things you can do to keep it running efficiently.

clean it. Remove the filter and clean it out, even if it looks relatively clean. A dirty or partially clogged filter can reduce efficiency dramatically.
wipe it down. Using a cloth, carefully wipe the outer coils or grill. (Be very careful – the grate is very sharp and can slice easily!)
inspect it. After you remove the filter, check the area around the compressor and coils. Vacuum it out if it is …

The number one cause of air condioner problems is compressor failure. When this happens, a professional needs to contacted to replace the compressor. However, many other air conditioner problems are a little simpler and easier to troubleshoot.
But a dirty filter can make the unit behave like there is a compressor problem. When the filter is dirty and air flow into (and our of) the unit is severly limited, in most air conditioners the compressor will not turn on. This is because there is insufficient circulation for proper efficient operation. And …

So the last experiment was disappointing, because it appeared that plastic did very little to prevent heat loss for your leaky hallway window. Things aren’t looking so good for the thin plastic as insulation.
Luckily, we have another scenario. Plastic over part of a window has come “undone” giving us the perfect side by side comparison of surface temperatures over a window with and without plastic – without interfering sunshine and the heat from solar convection.

This question is important to many homeowners and renters because we believe that placing plastic over our windows will halep us save energy on cold winter days and nights. Some plastic makers claim that plastic adds at least 1R value to the window.
I doubt this to be true. But using the information presented in the home energy audit kit, we can easily see heat loss with and without the plastic to see how much of a difference it makes.

Finding and setting the optimal temperature may be a science in itself. You have to take into account the heat you use with your comfort level based on your activity.
For example is it necessary to have the heat turned way up at night while you’re asleep in your bed?
Do you need the heat turned off at any time?
You need to find the balance that suits you best.
I suggest playing with it some, but don’t make it too high or low.
In the winter set it no higher than 68 or 70 …

Basically, make sure the thermostat location isn’t too hot, or too drafty. The thermostat measures the temperature and locating it in either location can throw off the reading.
The effects can be disastrous for your utility bill.
The area might be warm, so the thermostat will be tricked into thinking the heat has done its job and turn it off. Actually, just the area where the thermostat is located is warm because it is directly over or very close to a heating vent.
The opposite is true as well. If …

Perhaps you have a few window air conditioner units for a few rooms of your house, rather than having central air.
That’s fine. In fact, it is much cheaper to operate if you stay in a couple of rooms most of the time.
Make sure they are working properly and efficiently. Most of them today are built to run pretty quietly. So if your unit starts …

Wait until night or evening (or on a cool day) to do chores or activities that generate heat.
Any additional heat you generate will just make the A/C work harder and longer.
Such activities include:

Baking or using the oven
Washing Dishes / Running Dishwasher
Laundry