Do you have to replace the dryer everytime you replace the compressor?

I put a new compressor into a car %26amp; I know its recommended that you replace the dryer as well, but is it absolutely necessary?





Also, the car is fitted with a retro...If I used the R34 instead of the preferred R12, will it be as cold/efficient?


Thx.
Do you have to replace the dryer everytime you replace the compressor?
I hope you didnt do it yourself..Unless you are qualified.





this will explain the Dryer/compressor deal...


http://www.aa1car.com/library/2003/cm503...
Do you have to replace the dryer everytime you replace the compressor?
Generally you should replace the receiver dryer every 12 months but if there is nothing wrong with the system why bother... R12 got banned in Australia about 10 years ago as it is Ozone depleting. R34 i think is the latest gas but over here everybody uses R134a You need to change all the o'rings and oil to make it compatible. R134a is not as cold as R12 but you wont really notice it ( unless you libe in the desert) some systems you can adjust the TX valve to set the temp.