No Sweat

By Chandra Orr

January 21, 2011 6 min read

Keep your cool this summer by keeping an eye on your vehicle's air conditioning, because even a small decrease in performance could indicate a larger problem on the horizon -- and a costly repair bill.

"The biggest benefit from regular AC service is to find a small problem and fix it before it becomes a large, expensive problem," says Randy Ford, owner of Catalina Automotive, an auto service multiplex.

For example, strange sounds that start and stop with the use of the AC may point to problems with the compressor or clutch, problems that quickly can affect other areas of the engine.

"The compressor is the source of more than half of AC system problems," Ford explains. "Major compressor failures are impossible to predict, but often the system shows you pending seal leaks or other problems before failure occurs. Replacing a compressor with leaking seals before failure can cost you up to $700, but that's a bargain compared with an internal compressor failure that sends small bits of metallic shrapnel through the sealed system. That can exceed $2,000."

*Test It Out

"There's a simple test for any AC system," says Paul DeGuiseppi, manager of service training for the Mobile Air Conditioning Society Worldwide, a nonprofit trade association. "Set all the controls for maximum cooling; close all the doors and windows; start the engine, and run it for about five minutes. If the temperature from the panel outlets lowers, there is a good chance the system is operating properly."

If you have a thermometer handy, place it in the center air outlet. On a warm day, a healthy air conditioner should lower the temperature to 50 F, DeGuiseppi says, and if the system is functioning properly, it shouldn't need additional maintenance.

However, if your car isn't cooling off as it once did, it's time to schedule a checkup. You may have a refrigerant leak, and a little attention now can prevent a lot of stress later.

"In some instances of a small leak, the system can be temporarily recharged with refrigerant to restore cooling, but this is only temporary, and a repair is in your future," Ford says.

Most auto supply stores sell do-it-yourself refrigerant refill kits for about $50, but beware. Overfilling the refrigerant decreases performance and can damage the cooling unit, so follow the enclosed instructions carefully -- or leave it to the pros.

At the service station, a typical AC system inspection with a refill costs about $150, Ford says. During servicing, the mechanic will perform a thorough external inspection, test the unit's performance and measure the refrigerant pressure. The mechanic also will check for refrigerant leaks, faulty seals, deteriorating hoses, malfunctioning pressure switches and worn-out drive belts.

*Check the Filter

Even if your vehicle's AC is in top working condition, it may need a little TLC. If it smells musty, check the filter.

"If your vehicle is a model year 2000 or newer, there's a good chance it is equipped with a cabin air filter. However, many motorists have never heard of a cabin air filter," says Rich White, executive director for the Car Care Council, a consumer education initiative spearheaded by the Automotive Aftermarket Industry Association.

The filter prevents bugs and debris from entering the AC unit and removes pollen, bacteria, pollutants and allergens from the air entering the cabin, but if it's been a while since you've had it replaced, the air inside the car may be dirtier than the air outside.

The Car Care Council recommends replacing the filter every 12,000 to 15,000 miles. In areas with heavy smog or other contaminants, it should be replaced more frequently. Used filters should not be cleaned and reinstalled.

*Cool Off Quickly

Don't let gas prices scare you away from using the air conditioning. Running the AC has a minimal impact on fuel efficiency, Ford says, and it's actually more efficient than driving with the windows open, which causes drag. However, even the best AC needs a little help on hot summer days.

The cooler the interior is to start with the faster the AC will do its job, so crack a window when you park your car to help reduce heat buildup. When you return, vent the hot air quickly by opening all the windows or opening the doors.

When you first turn on the air conditioning, set it to "max" and "rec" to recirculate and move the greatest volume of air. Once the cabin reaches a comfortable temperature, switch the system back to normal to pull in air from the outside, which will help prevent that musty smell from building up. Be sure to turn down the fan, as well. The lower blower speed produces colder air from the system.

Automatic Temperature Control systems operate differently than manual systems, but in general, drivers can get the same quick cool-down by setting the temperature as low as possible at first and then adjusting it for comfort once the heat dissipates.

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