1990 Mazda Miata converted system R12 to R134

warrenJ · Posted at Tue Aug 26, 2008 2:05 pm

Air Conditioning problem
1990 Mazda Miata 4 cyl Two Wheel Drive Manual 136000 miles
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my compressor cluth locked up...so in replacing the compressor and clutch as they are one pc we converted to R134 since the compressor came loaded with 134....found hole in evaporator and replaced it along with Receiver dryer and expansion valvle.....does not cool below 52 and seems to go between 52 and 56 depending on ambient temp. ANy ideas as to what could be wrong...I was told the conversion would be slightly less effecient but not really noticeable ...but now we are all scratching our heads as to how to resolve the problem

merlin2021 · Posted at Wed Aug 27, 2008 12:47 pm

You changed ALL the oil? This uses PAG oil, not compatable with R12...and do not use the same amount of R134 as R12, use less.

warrenJ · Posted at Wed Aug 27, 2008 6:54 pm

Yes the system was vacumed down and then filled with appropriate oil and freon. I will have to double check the amount of Freon used..I know the pressure were reading right the first time....We vacumed out the system again and refilled it.....I have to double check but one of the techs mentioned he thought the pressure readings were not where they were supposed to be....We even changed out the compressor under warranty to see if that would fix the problem but it is cooling even worse than before

merlin2021 · Posted at Thu Aug 28, 2008 9:54 am

Try replacing the reciever/drier, and the expansion valve. Low side sould be 30-40 and high 150-200 on an 80 degree day.

warrenJ · Posted at Fri Aug 29, 2008 11:26 am

Yes all components except the condenser have all be replaced and the compressor twice......we are thinking of vacuming down the system and trying R12 as that is what the system was designed for....any othe ideas as to why the R134 wont work .. Do you know anything about the product Freeze 12 they tought it as a better replacement for R12 than R134.....I assumed it was a marketing gimmick and really R134 in disguise....what are your thoughts

merlin2021 · Posted at Sat Aug 30, 2008 12:43 am

R12 is not sold in the USA anymore...freeze12 is not R12. Expansion valve in the evap core may need to be replaced. Call Mazda to see if it needs a different valve than the stock valve. Do you have the h & L side readings?
http://www.teamchicago.com/imperial/imp-ac.htm
Read about conversion here....and the Govt website
http://www.epa.gov/ozone/title6/609/index.html