Arrived for home care and the customer said he had a weird smell coming from crawl space to main floor . Completed homecare and checked all electrical and ignition components on both systems in heat mode. Checked all electrical and refrigeration components in Ac mode for both units. Found crawl space main unit low on refrigeration. Found biological growth all over the evap coil and inside the evap coil for crawlspace unit. Found supply plenum for crawlspace area with biological growth. Recommend a complete AC system and supply plenum replacement for crawlspace area unit. Reliable heating and air only changed the furnace units . Customer has only lived in the home since July 25.