Only a concern if the suction pressure is below atmospheric.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


"Molly Brown" wrote in message
...

Just make sure that they thoroughly evacuate the system before it is
re-charged. Many technicians will not take the time and it does take a
few hours. The best way is to evacuate and then put in some nitrogen
and then evacuate again and repeat.