Summer is getting closer and all of us will be depending on our air conditioners to keep us cool, so we thought it might be a good idea to discuss a few common air conditioning questions. Our June 2002 issue of Car Care Tips discussed types of refrigerants and our procedure for identifying leaks.
What is the best way to get maximum efficiency from my air conditioner?
We get asked this a lot. First, let's clarify the terminology of your A/C controls. The fan speed is controlled by the fan switch or blower switch. The different modes of air output are usually controlled by either a sliding lever, a rotary switch or a series of push buttons. These control whether the air comes out on the floor, through the dash vents, through the defroster vents or a combination of the above. Some of these automatically turn on the A/C compressor, while other cars use a separate button to command the compressor on. Also, some have "MAX" and "NORMAL" positions of the mode switch, while others have a separate button or lever to change between "RECIRCULATE" and "OUTSIDE AIR" positions. Even others automatically go to "MAX" or "RECIRCULATE" when the temperature control is placed in its coldest setting. These can be the most important things to remember, because to get the most efficiency from your A/C system, it's best to cool off a hot car by lowering the windows slightly, turning the A/C to "NORMAL" or "OUTSIDE AIR" and putting the blower on a medium speed. This takes outside air, cools it and forces the hotter inside air out through the open windows. Once the air in the car has cooled down to a more comfortable temperature, switch to "RECIRCULATE" or "MAX" so the system can take the already cooled inside air and recirculate it so it will gradually get colder and colder. Then make yourself comfortable by adjusting blower speed. This procedure will cool your car quicker, keep it cooler and even save you some gas by not causing the system to run continuously.
What about that musty odor?
More and more we hear this question, and it is usually coming from owners of later model vehicles. The odor is caused by fungus, bacteria and microbes growing inside the evaporator core case. The moisture-laden environment caused by condensation is quite conducive to the growth of these organisms. The automakers downsized these evaporator cases, added more fins and packed them closer together on the evaporators, which made them more prone to trap moisture and contribute to the growth of fungus. There are several methods to combat this growth. Some newer vehicles come with a device to run the A/C blower for a period of time after the vehicle is shut off. This dries out the evaporator case. There are also chemical fixes: from as simple as spraying Lysol into the A/C air intake to as complex as drilling a hole in the evaporator case, spraying in an expanding foam fungicide then letting it convert to a hardened shell of fungicide. One of the least expensive, although not the most practical methods, would be to turn off the A/C compressor a mile or so before you get where you're going, but leave the blower running to allow the evaporator to dry out.