For existing blockages that are already triggering an overflow, consult your local plumbing provider. A qualified technician will remove the blockage from the drain pipe using pressurized air or suction, or by snaking the line. After the line is clear, issues causing the blockage will be addressed. Frequently, mold or algae growth in the warm, wet environment of the drain pan is the culprit. If evidence of active mold or algae is discovered, the technician will disinfect the drain system, then install time-release biocide tablets or cartridge to continue inhibiting mold and algae growth throughout the cooling season.