I have a 2010 arctic cat crossfire 800 and this year I was doing lots of trail riding. The overheat light came on 4 or 5 times over the winter. So this summer I went to fire it up and I noticed that there was no coolant in the resovoir. I opened the rad cap and looked inside and seen that the level was right where the resovoir turns into the tube, right at the bottom. My question is should I be worried of air in the lines?