There are a few things that could be going on - first and many people have commented on this - is that the Arctic coils have a reallllly weird taste at first. When I first got my arctic I couldn't figure out why it tasted like poison - then about half a tank to a tank later and it tasted as amazing as before. So, it is possible that what you are tasting is that arctic funk. It really does go away - I'd also recommend that if you have other juices that you don't like as much putting them in your tank during the 'funk' period of time. That way you're not wasting the good stuff.
The other reason it might not taste as amazing as you remember could be 'Vapors Tongue' - can happen if you're vaping the same flavour obsessively, if you're dehydrated, if you've recently quit smoking. It's an olfactory exhaustion - your tongue just can't taste it anymore because you've done it so much. The first time it happened to me I thought that my mod was broken. Then I made sure to drink lots of water and also to buy a whole bunch of different flavours in different flavour profiles. Then when I went back to the juice I had gotten vapors tongue from it tasted as amazing as I had remembered.
Good luck!