first of all it's called the evaporator coil.the condenser coil is the one outside.can you take the drain hose off and funnel some bleach into that stub that the hose connects to.if not then i wouldn't even worry about it.some of them are a real pain requiring you to remove a half a dozen screws along with the flue pipe to gain access to the coil.just clear the drain and you should be ok.