No one in my immediate family or my extended family drives "Brand New" cars. The reason is simple; they have me to keep their used cars running like they were "Brand New" cars. A few weeks ago, my daughter in-law bought a 2001 Ford SUV from a private seller. The body and interior were spotless. The SUV had been well cared for, but there were a few things wrong with it, one of which was the air conditioner did nothing but blow warm air. With seven kids to transport, air conditioning was a priority for her, so she called me and asked me when I could look at it. My wife loves calls like that because she gets to spend time with all the grand kids while we are out in the garage/barn getting our hands dirty. My daughter in-law is an excellent mechanic's helper. As I suspected, all it needed was recharging.

R12 or R134a

In 1995, car manufacturers switched from using R12 to R134a as a refrigerant. The first thing you need to do is ascertain which refrigerant you system uses. You need to do this for several reasons. First, never mix the two types of refrigerants. Second, if the system uses R12, you will have to take the car to a professional. You need to be certified by the EPA to work with R12. Third, a professional who has the proper refrigerant recovery system should retrofit an R12 system for R134a. Releasing Freon into the atmosphere not only damages the Ozone layer; it is against the law and carries a stiff fine.

The easiest way to determine the refrigerant used in your vehicle's air conditioner is to take a close look at the "High Side" and "Low Side" fittings. The High Side and Low Side service fittings are threaded fittings on R12 systems with 3/8 and 7/16-inch threads. You can always tell the high pressure from the low-pressure side of a refrigerant system by the size of the lines. The high-pressure side uses smaller tubing and fittings than the low-pressure side. Systems using R134a have Quick-Disconnect fittings. 13 mm and 16 mm respectively.

Safety Precautions To Be Observed

Always wear safety glasses and mechanic's gloves when working with refrigerants. The chilling effect of getting liquid refrigerants on your skin is a case frostbite. Getting liquid refrigerants in your eyes may lead to blindness.

Things That You Will Need

1. A service manual for your vehicle. A service manual will help you locate the service fittings as well as give vital specifications for your system

1. An air conditioning manifold gauge set. You can recharge your system without monitoring the process with these gauges but the use of these gauges is highly recommended. Invest in a professional set of gauges designed for use with R134a. A professional manifold gauge set will cost between $40 to $80, but they will last a lifetime with proper care.

1. Refrigerant recharging kit. Some DIY recharging kits come with a low side pressure gauge and I recommend one of those kits if you do not invest in the manifold gauge set. The R134a available to the DIY person usually comes in 14-ounce cans. Most new cars use 14 to 28 ounces of refrigerant in their system so buy two cans.

Recharging Without Manifold Gauges

1. Connect the recharging hose and valve that came with the recharging kit to the can of R134a.

1. Turn the valve all the way clockwise to puncture the can of refrigerant.

1. Open the valve slowly to admit a small amount of refrigerant into the line to blow out any dirt in the line. You do not want any dirt that may have been in the hose entering the system. Close the valve, on the refrigerant tightly.

1. Connect the service hose to the service fitting on the low-pressure side of the system. Make this connection as quickly as possible to keep refrigerant that is in the system from escaping. DANGER: Under no circumstances connect the service hose to the system's high-side service fitting. The high-side pressure of an operating system may exceed the burst pressure of the refrigerant can causing the can to explode like a hand grenade. You should not be able to make this mistake because the high-pressure service fitting is smaller than the low-pressure fitting but I would be remiss if I did not warn you of the danger.

2. Start the engine and turn the air conditioner to its "HIGH" position. The compressor clutch should engage. If the clutch does not engage because of low system pressure, you will have to bypass the low-pressure cutout switch. Locate a single wire near the front of the compressor and unplug it. Using a fused jumper wire, connect the terminal on the compressor directly to the positive battery terminal. The clutch should now engage and the compressor should start to run.

3. With the refrigerant can in an upright position, open the valve fully. Keep the refrigerant can in an upright position, you do not want any liquid refrigerant entering the compressor any liquid refrigerant entering the system can cause irreparable damage to the compressor. It may take 10 minutes or longer for the compressor to suck all refrigerant from the can.

4. Monitor the low-pressure gauge that came with the recharging kit. Stop adding refrigerant to the system when the gauge reads between 25 and 40 psi. The system is full and you do not want to overcharge the system. If the low-pressure gauge reads over 50 psi, the system is overcharged and you will need to release some of the refrigerant into the atmosphere. This is both safe and legal to do with R134a.

5. With the system fully charged, shut the engine off. Closed the valve on the Freon container and disconnect it from the system.

6. Remove the fused jumper and plug the compressor clutch control wire back in the connector.

7. Replace all dust caps.

How To Connect and Use Manifold Gauges

1. Read the instructions that came with your manifold gauges.

2. The manifold gauges and hoses are colored coded. The "Red" hose connects to the systems high-side service fitting. The "Blue" hose connects to the systems low-side service fitting.

3. The "Yellow" hose connects to the refrigerant container or to a vacuum pump for system evacuation.

4. The high-side gauge will read between 225 and 250 psi with a fully charged R134a system.

Your system is now blowing ice-cold air but if it stops working again after a few days, weeks, or months, there is a leak in the system that you will need to repair. I will explain how to troubleshoot for system leaks in another article.