IS2402FAST wrote:IT DOSENT MATTER IF IT HAS 134A OR R22(OLDER CARS HAVE THIS) CAUSE U CAN PUT IT IN AND MIX IT TOGETHER. THEY SAY YOU HAVE TO PUMP IT OUT BUT I DIDNT IN MINE AND THE A/C WORKS FINE I HAVE DONE THIS IN SEVRAL OTHER CARS THAT I HAVE OWNED
Older cars used R12, not R22 (R22 is used in home A/C units).
R134 and R12 are *not compatible* and should not be mixed. In fact, it's a violation of US Federal law (if you're in the US) to add anything *but* R12 to a system already containing R12. If you've got a good working R12 system that is simply low, top it off with R12. R12 is a much more efficient refrigerant than R134.
The biggest problem with mixing R12 and R134 is the lubricant used. R12 systems use mineral oil, while R134 uses PAG. R134 is not compatible with mineral oil. What does compatible mean in this case? It means that R134 won't properly distribute the lubricant through the system. There are a number of side effects to this... mineral oil will collect in the "low" points in the system, impairing system function. Insufficient lubrication will reach the seals and compressor, resulting in increased wear of these items.
Can you mix them? Sure. Is it a good idea? No. Will it eventually cause system failure? Probably.
Doesn't matter if you've done it before, it's not a good idea.
- DaveCertified Motor Vehicle Air Conditioning Technician