In the summer when you ease into your oven-like car, you want it to cool down. Quickly.

Unfortunately, cars start to lose their cooling abilities as years pass and components age. If your car has lost that frigid edge, it might be time to recharge the air conditioner.

There are two ways to go about it: Do it yourself or through an auto shop.

Travis Mock, supervisor for AAA Auto Repair, suggested car owners get an AC inspection once a year and recharge the system every couple of years. An inspection will check the condition of the belts, whether the fans are properly operating, measure the high- and low-side pressures and the temperature coming from the vent.

When an auto shop recharges an AC system, the technician pulls out all the old refrigerant and moisture and adds the proper amount of refrigerant and oil. Expect to pay $80 to $100 to have a reputable shop recharge your AC.

Cars made before 1994 used R-12 refrigerant and must be converted to the more environmentally friendly R-134. Older systems also used mineral oil and now must use PAG oil to lubricate the compressor.

The problem for do-it-yourselfers is that PAG oil can’t be added without using sophisticated equipment. And if the AC system runs too low on PAG oil, it could seize the very expensive compressor.

Some people would rather pay for a $20 do-it-yourself recharging kit instead. On the packaging, the directions seem simple: Spray the refrigerant from the can provided into your car’s AC system, and it will recharge.

There are a few problems with that. First, you have no way to verify the high-side and low-side pressures, which can’t be done without special equipment.

And many of the DIY cans contain an ingredient called Stop Leak, which contaminates an AC system. Any reputable shop won’t service a car that has Stop Leak in it, and the shop has a gauge that can tell if it has been used.

“Once that gets in the AC system, it could cause a lot of headache and damage,” Mock said. “Shops don’t want to reintroduce Stop Leak. It will contaminate all of their equipment, so they won’t service it.”

Not every can contains Stop Leak, but many do. It should be listed on the can.

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Avoiding Stop Leak is only one issue, though. Unless you have access to a vacuum pump and specialized AC gauges, there’s no way of knowing if you’ve overcharged the system and added too much refrigerant.

Some people believe that adding extra will make the air cooler. However, if there’s too much in the system, the car will respond by blowing hot air. An auto shop will use gauges to determine the correct amount to be added.

“We see a ton of cars that come in that the cars are overcharged,” Mock said. “If there’s too much refrigerant, it will blow hot, too. There has to be the proper amount.”

The gauge supplied in the do-it-yourself kit can’t tell the difference between true refrigerant and moisture. And most do-it-yourself kits don’t allow you to fully drain the system.

“Basically, it’s not worth the hassle to possibly save a few bucks,” Mock said. “And for most people, it ends up costing way more to make things right.”

AAA is an automotive resource. For more information, go to

Valerie Vinyard is a public affairs specialist with AAA Arizona. Contact her at or at 258-0518.