View Full Version : Retrofitting A/C system

04-09-2000, 06:32 PM
I am planning to retrofit my a/c system from R-12 to R-134A. I have the kit to do it but have been told that I should flush the system first. The kit says that I do not have to flush anything, just add the Poly oil and R-134A. The system has been nonoperational for the last two years but has not been exposed to the outside air. I will vaccum the system out first then charge with R-134A. Any ideas? (this is in an 88 K-5 Blazer)

John DiMartino
04-11-2000, 05:50 PM
We use only ester oil in our retrofits,and we dont flush unless it blew a compressor or something.you should consider installing a new orifice tube while you are at it,the screen may be plugging up with metal from a compressor on its way out,and you will need the system working at 100%,because you are going to lose about 10% capacity from the conversion,if it was cooling borderline before you wont be happy now.<p>----------<br>John D<br>

04-11-2000, 08:36 PM
John; Should I replace the accumulator? If i have to replace the oriface then I will have to open the system up and expose it to moisture. I suppose I will have to install a high pressure cutoff switch also because of the higher pressure of the R-134A? What about the compatability of the oil in the compressor? Thanks in advance. JB

04-11-2000, 08:48 PM
jb, A flush of the system should not be neccesary unless you had contamination due to hose deteriation or metal contamination from bad compresser.We have not seen any performance loss on any of the hundreds of conversions we have done . I think that is <br>just simply untrue. The r-134 is actually more stable and helps with compresser longetivity [we have some vehicles with over 150,000 miles that are still going strong on original compresser and 134 from factory].. hope this helps . By the way .. a factory fan clutch is crucial to low rpm ac performance [or better yet ,, twin electrics] just be aware of cheeso fan clutches, they greatly effect pressures and performance of ac ... see ya

04-11-2000, 08:53 PM
jb , No fancy high pressure switches are neccecary , accumulater not necc either , system will operate at same pressures as before. Replacing orfice and a good vacume is a good idea though,

04-11-2000, 08:58 PM
ester oil is compatible with oil in r12 // just dont over do it [too much is bad] just follow retrofit instructions