A friend converted my air conditioner 3 years ago from R12 to R134. However, I have noticed that my air con stopped cooling a week ago.I would like to recharge the system but I don't know how to go about it.Can anyone pls. tell me what to do.I already bought 2 cans of R134 and charging kit. Thanks in advance for any advice.

You should ask your friend for help, if possible. Auto parts stores sell refrigerant/charge kits like doing a recharge is as simple as changing your oil. It is not.

Charging the AC is fairly simple, but mistakes and missing the details can be dangerous.
For example, the R134 can gets very cold when it is being emptied so you must use gloves.
Goggles (not just glasses) are also recommended when handling refrigerants in case a spurt escapes during a disconnect and hits you before evaporating (and freezing whatever it landed on - hopefully not your eyeball). Not to mention the risk of rupturing the can by connecting to the high pressure side of the compressor or the risks of over-charging (both to yourself and to your AC equipment).

But, if you know exactly how your car's AC works and you understand the risks, it is not a very difficult job.

Also, the R134 conversion on my '91 included a new receiver/drier. The charging port on R134 systems is on the receiver/drier, near the passenger side firewall, not the compressor (as suggested in another post).

Be cautious, get some good help/instructions, and good luck.

Oh, and happy bricking.

Todd

Try adding a little refrigerant! Some of these "recharging kits" come with a little gauge on the line which makes it simple. The port to plug into is on the rear of the compressor, it should have a plastic cap that unscrews.(quite difficult to access) Then the charging kit should have a hose with a snap on type fitting on the end..plug it in on the low pressure (large diameter) side, leave the can right side up and let your A/C compressor suck in some of that 134a!