Upon arrival checked over system investigated water dripping from ceiling. Checked over package Unit on roof. Drain pan is leaking water into system and then further down into ceiling. Drain pan is metal and has significant amount of rust, erosion and oxidation which has caused water to leak. Preformed safety inspection on heat exchangers found multiple holes and cracks in heat exchangers. Heat exchangers must be sealed, during the heating season with a crack or hole there is a greater possibility of carbon monoxide leaking into space, system has 13 different holes, and cracks. Would strongly recommend to not run heat until Heat Exchangers are replaced or system is replaced. System is running on R22 refrigerant system holds 6 pounds 6 ounces, system is low on R22 roughly 1-2 pounds.R22 is no longer in production due to EPA regulations, supply of R22 is dwindling, there is dye present in system, this indicates there is a known leak inside. If drain metal drain pan is replaced all refrig