It makes no difference whether the car is new or old, whether it's valuable or just about ready for the scrap-yard, don't touch the air-conditioning yourself. This has nothing to do with what it costs and we haven't been bribed by any workshops either. You'll see what we mean, the bare facts are simply irrefutable.
Let's start with some really serious damage, e.g., to the compressor. What can go wrong there, if one replaces it oneself? Plenty, because you may have opened the circuit at a point where there is still refrigerant inside. Both the environmentalists and the legislators agree that in this case, suctioning it out and disposing of it, is the correct method.
So, basically, you can go to a disposal unit and have the system emptied. Then you can tinker around with the compressor, or for my part, also the condenser or any other component. Indeed, what then? Do you want to employ one of those strange filling sets?, the first time, you need one with a manometer and they're bit more expensive, after that it becomes somewhat cheaper because one can buy refills.
These filling sets have the disadvantage, that they measure the pressure, and if it's too low, they tell you to fill up accordingly. Once again, both the environmentalists and the legislators are also against that. The filling up is prohibited, if it hasn't been checked that the system is one hundred percent leak-tight.
Then there's the filling up according to pressure. Wrong again, since a proper service-machine removes the refrigerant from the system, measures the weight and then determines the amount to be added. Somewhere in the engine compartment you'll find a sticker with the specifications (picture 5). The filling sets can't work this way, because they don't (or can't) carry out any weight determination.
And what do the filling sets put into the system? This you should check very carefully. It may, e.g., be CO2. At first, that sounds good, because that is exactly the refrigerant (R 744), that certain manufacturers want to use in the future, because they are rejecting the new R123yf refrigerant, due to it being especially dangerous if exposed to fire.
You could say, that the usage of carbon dioxide at such an early stage is a step in the right direction. It's not, because a system which has been filled with CO2, has to be run using substantially higher pressures. The expensive modification of the air-conditioner, is precisely why not all the manufacturers are going along with this.
Thus, the more you refill, the weaker the system is. Then there is also the oil. During a normal service, this is also suctioned off and weighed. As you can probably imagine, also the amount of oil is prescribed. Indeed, perhaps even more important, the oil must fit to the refrigerant. This basically means, that each refrigerant has its own oil.
Do you know, whether the oil in your vehicle is compatible with the added refrigerant? As you can see, there is a growing pile of unanswered questions. As far as engine-oil is concerned, you're finical, but here, you're risking very expensive compressor damage. There is indeed, another reason, why you shouldn't do-it-yourself, you won't be able to guarantee that there are no shavings left in the system.
Shavings are something really wonderful. They are one of the few possibilities that you have, to completely demolish an expensive spare-part after only a few minutes of standing time. The manufacturers urgently recommend rinsing as a protection against shavings in a repaired air-conditioner.
This is something, that you can hardly do yourself. Not only because of the lack of suitable disposal measures. The vacuum-pump must also be pretty powerful. And then there's the manometer for high- and low pressure. The latter should also even indicate the vacuum. Since before the refilling finally takes place, the system must hold a constant vacuum for a longer period of time. 08/14