I had the dealer do an R134A conversion on my '88, it was about 250 with the new refigerant. I also had an '84 Land Cruiser converted to R134A. So far on a 90 day the coldest I've got the M down to is 37, the Land Cruiser I got down to 18. I'd say thats more than enough cooling power. Both A/Cs weren't working when I bought the cars, so I had them converted and charged, so I can't say how cold they got on R12.