I recently replaced evaporator for aircon, replaced radiator cap been all checked my mechanic he said vehicle all good. Air con came good 4 awhile after radiator cap changed, but now air con not cold no more and all of sudden check engine light on dash. ? Can a failing battery be 1 of many causes that can cause the Check Engine Light to come on too? I've been noticing some small things about the way the car acts concerning I think the battery, not entirely sure.