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My 396 ss has under dash A/C with the old fridgidaire compressor. Is has been converted to 134A, as I have been told that it is a "universal" system. It feels cool, but I can see bubbles in the dryer sight glass. Can I, or better yet, should I top the system off with 134A until the bubbles are gone, or is there a chance of damaging something? Thanks!
 

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I've had a couple of AC systems converted to the new stuff and have been very dissappointed in the results. The newer systems seem ok, I just don't think the old systems work very good converted to 134.
Thats the characteristic of converting an existing R12 system to 134. R12 has always been able to cool more then 134 has regardless of if its an older car or a newer car with a 134 system. R12 carries out the heat better then 134 because its made up differently, like scientificly if you will. Thats not to say a 134 system isnt as good. Many 134 systems can make it pretty chilly inside a vehicle too.

Problem is, 134 does not really work as well on R12 applications. Some will even damage a compressor over time.
 

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Every 134 system (R12 conversion) I have seen that performs poorly does so because the system has been OVER CHARGED! It is very easy to over charge a system with 134.

Go to the local A/C guy and have the system chaged with an A/C machine that will meter the EXACT amount of 134 needed for your system. Proper charging of the system has fixed EVERY poor performing 134 conversion I have helped resolve.
 

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I agree with the overcharging of a system that affects its performance. On any r12 to R134a conversion you only install 80% of the original charge. For example if the system took 3.0 lbs of R12, then you install 2.4 lbs R134a. Also when doing a retro fit you should vacuum the system for about an hour to get all the old oil and moisture out of the system and install the new PAG oil.
 

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I agree go to a shop that specializes in A/C and have them suck down the system and add the correct amount. Even at that a 134a system will probably never cool as well as your old R12 system.
 
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