AC; be Cool, Safe, Eco Friendly.

I had no intention of writing about AC, but after Jimbob made a passing remark about getting his AC serviced and the Tech was going to charge him to totally refill the system, I thought I should pass my remarks now on "Earth Day."
First, a little history: Car AC was first used around 1940 in a Packard. It didn't work well but started a trend. By the late 50's, AC was becoming popular and R-12 refrigerant was being widely used. By the late 70's R-12 was confirmed to be a significant factor in Ozone depletion. In 1987 The Montreal Protocol was signed and by the mid 90's production of R-12 was phased out (In developed countries) in favour of R-134A. About 10 years later the Kyoto Protocol went into effect and by 2010 CFC's were being phased out in developing countries. After 2012, European cars no longer were allowed to use R-134A and have switched to HFO-1234yf, which is being phased in here in North America, as I write this. It is currently more pricey than R-134A but will have much less negative affect on the environment, and will come down in price as it's use becomes widespread.
Servicing AC: Service Techs must be licenced to fix AC systems in Canada and the US. It is against the law to release refrigerants to the atmosphere! Period. ( I could lose my licence for doing so) If your AC system is a touch low, the appropriate refrigerant may be added. If there is a leak, the refrigerant left in the system must be captured in a proper AC service unit, where oil and contaminants are filtered. That refrigerant is weighed and held for reuse. The leak must be found and fixed, usually by the use of fluorescent dies and pressurizing the system with Nitrogen. After a successful repair, the system is vacumned down for 30 minutes or so and the recovered refrigerant is reused along with the proper amount of oil, and any extra refrigerant required to get the right total weight. A tag must be attached to the system indicating the repair, date and Tech signature. Ford adds the bright die at the factory so you can detect leaks before your compressor gets "pooched." Others may as well.
One of my pet peeves is the sale of cans of "top up" refrigerant like "Red Tech or Dura Cool." This stuff is not the proper refrigerant! It is "HC-12-A" which is a nice way of saying it's mostly Propane and Iso Butane. I've even seen videos showing how to charge your AC with pure Propane! Don't !!
If you have an old car in the US with R-12, a pro AC guy will have the proper equipment to service or convert it to R-134A. Recently learned that R-12 refills are not allowed in Canada anymore.
We used to keep an older AC service unit just for R-12 repairs. The problem now is that R-12 is hard to find , produced offshore and may contain bad things.
So, take your car to an AC pro for repairs. If they don't have the proper capture and reuse equipment, I suggest you go elsewhere. They should have a dedicated AC repair system and not be refilling from small cans.
A few years ago I worked at a Goodyear Store part time. They had great equipment and training. We had a customer come in for AC repairs because it snowed inside the car when the AC was on. He had added 3 cans of "top up" and the operating pressures were so high it overwhelmed the expansion valve and the evaporator frosted over. The repair included a new compressor, condenser, dryer unit and expansion valve. Total, over $1000.