Using A/C Recharge kits?

Once the system has sealer in it you'll probably have a hard time finding a shop that will touch it.

My foreman at work decided the price was too much to have a shop recharge the air in the family truckster, so he bought the kit you're talking about. He ended up paying for the kit, and paying the shop to do the job. Some guys should just pay to have it done, then to try and save a buck and have it backfire on you. You might have better luck though.

I am NOT familiar with that kit. As a rule, refrigeration is never safe. One wrong move and you lose a compressor, or an eye.

I'm not an expert on AC, but I do know enough what NOT to do. You don't touch them unless you know what you are doing. The pressures are very high and can cause serious injury. Overfilling is bad. Using any type of sealer is a potential problem and can do more harm than good in some circumstances.

Sometimes it is best to just pay the money.

Don't use a kit with a sealer. Use one with a lubricant or oil additive. Use the low/suction side only to fill while the AC compressor is on. Otherwise, the gauge may peg or blow, and you'll get faulty readings if it doesn't blow.

A sealer may cause permanent or intermittent blockage, killing the the AC. A blockage, at the very least, can be difficult to find. Expensive to repair.

The shop method should monitor the proper activation and deactivation of the high and low pressure switches, dryer, compressor and evaporator. Evacuate the system, diagnose any water or contaminants in the system, check for leaks, refill the system.

The described kit, minus the sealer, will work if all else is up to snuff, and done correctly.

Well, I wouldn't take it this far. Aftermarket refridgerant top-offs have been in use successfully for a long time. I've added R12 and R134A many times. It's best to have a set of guages since one can overcharge an AC unit, the (overly)simply guage that comes with most kits today serves quite well. You can't hook it up wrong since the high pressure port and the low pressure ports are different sizes. These kits don't make an AC technician out of the average car owner, but with prudence they can be useful.

circumstances.

Likewise I'm no AC expert - far from it. I have asked them about the use of these top-off kits though and have been told that for just topping off refrigerant, they are fine. You're right - they can be overfilled so it's important to watch the simple gauge that comes with the kit. It's no precision device, but it does serve a purpose. More is not better in AC.

Agreed as well, on the use of sealers. It's not uncommon for AC units to lose refrigerant over time and simply topping off can be all that is necessary to restore performance. If the system has significant leaks then magic sealants aren't the cure.

Don't use the leak sealer type of 134. I bought a can tap kit with 3000 psi hose and a gauge that make topping up, or a total recharge easy.

You can get R134A for about $8 bucks a can at WalMart, higher maybe at Autozone or Napa. You can get it with , or without, the lubricant.

In my case, the low side Schrader valve core was defective, so I replaced it and fully recharged the system.

If you KNOW it is fully discharged, as I did, you can recharge by weight. If not, use the pressure ranges on the gauge.

This tap kit WON'T fit the high side anyway, but your valves could be different so be sure that you have it installed on the right side.

GM compressors, at least some of them, are known for developing leaks at the shaft seal. A double lipped seal is available which helps or cures the situation. But, a topup is probably the cheapest and quickest way to get cool again.

I'd add a couple cautions 1 ... If using an 'Oil Shot ' make sure it's * Ester * based oil, which works with older R 12 systems

PAG oil is for new systems, that have never seen R 12 or Ester Oil

If you've got a garbage system, buy a R 134A can Tapper, and an Ester Based Oil shot, put the shot in, see if oil leaks anywhere, and if compressor stays running. Considering the small diameter holes in the orifice tube, I'd stay away from sealer !

2 ... Oxygenated R134A can be explosive, never use compressed air for testing !

Here is the site for a Dupont MSDS for R134A.

It is really pretty safe stuff.