Brothers of The Benz, All
Right in that no sealant is required on the "O" ring seals except for refrigirant oil.
No harm can come from anti-sieze compound applied to the male threads making sure none gets in the system.
It's unfortunant that we all weren't born rocket scientist.
We have to learn sometime.
Let's help those who ask for what knowledge someone has pasted on to us.
blau, if your system needs a hose and it is empty of freon; go ahead and replace it as has been suggested.
Take it to a refer shop for final service.
I might suggest you request that the compressor oil level be checked or in your case converting to 134A, the newer oil be added or changed.
blau, roll up your sleeves and dive in, you will be better for your effort.
Happy Trails Beep Beep from The Spiderman in Houston!!!