Originally Posted by
audiokong
opening a ac system makes the dryer susceptable to mositure, ruining the dryer, look it up any automotive text book will tell you to replace the dryer anytime you open the system, just a step to insure that you will not ruin the compressor of any other parts of the ac system, if you are just evacuating and recovering (not removing a line or a part from the system) no there is no need to.....
text book doesn't always equate to real life situations though. I have been working on A/C systems for quite some time and as long as I apply a vaccum to the system thus lowering the boiling point of the R134 than it will boil out the moisture from the system. I will agree it makes the dryer susceptable, but for the part he was replacing I wouldn't worry about it 9 times out 10.