Sorry I didn't use quotes, but I was refering to the original poster saying his system was blowing cold air at 30 deg.30 deg. Celsius not Fahrenheit
I'll vouch for that. Here in Alabama, my system (R134A conversion) blows at around 42deg with the ambient temp in the high 70's/low 80's. If I were to add any more refrigerant, I'm sure my pressure would have exceeded the max and would have shortened my compressor life. It blew slightly colder (about 2 degrees) back in the R12 days, but I'm completely satisfied with the conversion.Sorry I didn't use quotes, but I was refering to the original poster saying his system was blowing cold air at 30 deg.
Normal range is 36-48 deg while driving, max A/C with blower on high. To be sure I just looked at my anolog A/C thermometer that is always sticking out my register. That is were the acceptable range is. Any colder, especially on a 100 deg day indicates that it is over cooling.
Could be over charged or could have a bad pressure sensor that cycles the compressor too long or too often.
I also woudn't use "Rubbing Alcohol" as a solvent in A/C systems because it has a fairly high concentration of water which is what you are removing from the system with the vacuum pump. You are actually boiling the water out of the system because water boils at low temps when under vacuum.
If you are going to use something other than a commercial A/C sovent I would use "Denatured Alcohol"
If you have to replace freon every year, it's because you have a leak and not because the molecules are smaller. All cars have come with R134 for 15 or so years and it does not just leak out. I have been a mechanic for 21 years and I have never seen a car just leak because it uses R134.I do not dissagree with anything said in this thread about swapping over but, personally I would not bother to change from R12 to R134 in an R12 designed system.
To do R12 yourself first get a freon card and become leagal to use it.
The cert test is easy and it only cost 15 bucks when I did it a few years ago. Once you mail if off in a few weeks a brand new freon card that allows you to by R12 and R22 will arrive in the mail.
Then go to O Riley auto parts and spend 35 bucks (yes I know to damn much but it works) for a can of R12 and just charge up your system. It will then blow sweet COLD all day long and this is from a guy living in Houston Tx where it matters.
The issue is if the evaperator is not sized right you will not get the full cold potential the system is capable of and it you have small leaks it will be a hassle from then on.
The other option is to use HC12 http://www.foxtoolsupply.com/
I buy it from this guy but a lot of folks offer it. I have been using it for 3 years now in my 2000 jeep that had 134 in it from the factory and have been very happy since I changed, gotta love the sweet COLD.
Befor then my 134 leaked out all the time and I had to rechage it every year because of 134s small monicule size where HC12 with larger molecules does not leak so much. And damn it blows cold and does not deterorate the rubber etc.
Read up on R134 "issues" and you may change you mind on using it. There are alternatives. However if you decide to sell your car switch it back to 134 or 12 as very few professionals deal with it.
This is just one link but a google search will show more.
Appreciate your thoughts and link, Chomot.My point is with the very small leaks that are hard to find and can be costly to fix, 134a with the smaller moleculs amplifes the problem. A higher system standared of integrety is required to hold it in. A cheap fix is use a different refrigerant less suseptable to leaking.
I found a good 134a discussion here