Now that the weather is starting to get warmer, it's time to start thinking about getting the A/C system in top shape. I'm thinking that as long as I'm going to be messing with it, I'll go through the whole system and then won't have to worry about it again for a long time. First on the list will be new hoses and "O" rings everywhere. This will be on an '88 S4 without the rear A/C. Is there a complete lising somewhere of all of the "O" rings in the system and what the sizes of them are?

The next thing to deal with is the refrigerant issue. The car has never been converted from the original R12 refrigerant. Is it a good idea to convert to R134? What all needs to be changed when a 928 with an R12 system is converted to R134? Is a complete flush of everything required? Will the system still provide sufficient cooling after a conversion to R134? What about the Envirosafe refrigerant that I've seen online? (http://autorefrigerants.com/Envirotechnical.htm) Is it really a drop in replacement for the R12 system in a 928, and if so does it work well in the 928's R12system? Would it be easy to get a refill of a system that has Envirosafe in it if it needs some? What about the Freeze12 stuff? (www.freeze12.com) Is it better to just join the R134 masses? They are still using R134 in new cars, aren't they?

Lots of questions. After doing some reading online, the refrigerant issue just seems to be even more confusing than it was before. I'm hoping to get some feedback from some people here with experience on the subject, and ideally in regards to the 928's R12 system in particular.

 

I used duracool in my car and it works great!

 

You will lose 10-12% cooling efficiency going to 134; where do you live and drive?. There is no drop in replacement, claims to the contrary. A flush is required; I would change to barrier hoses at the minimum.

 

I did the R-134a conversion on my '89 S4 almost 8 years ago now. It's been trouble-free since then. Oriiginal owner had it checked and recharged ath the dealer a few times a year prior to my ownership, so I had to do something.

In spite of the "loss of performance" claims when you change from R12 to $134a, I find that I can easily see cenetr vent temps into the high teens with the new gas, with the freeze switch broken, cruising in 90+ ambients in SoCal.. With the new switch installed and adjusted, it cycles between 34F and 38F temperatures on the switch. Will you get these same results? Yes, if your compressor is still in good shape, if the evaporator is clean, and you have the correct amount of the correct oil and the right amount of refrigerant. My system is somewhat undercharged, relative to the amount of R12 recommended.

The later cars with R-134a use a different pressure switch, one that open on pressure too low like the original, and alos opens on pressure too high. the 'too high' open is important in a conversion car, where the R134a likes to have a bigger condenser. The 928 has a big condenser, but the switch provides a little insurance in the case where a fan fails.

Go for the conversion.