3.) You’re smelling or tasting a fruity, sweet scent in the cabin
Technically, ethylene glycol is an odourless compound. However, in large enough quantities, you might start being able to taste the gas, which can be construed as a smell. In any case, this means there is a very serious accumulation of coolant gas in the cabin. Roll down your windows when driving to the aircon service centre to avoid inhaling more ethylene glycol than is necessary.