I have a 98 SAAB 900S with a long standing (years) wet carpet just above the spare tire. It appears to just be water. I have removed and replaced the floor gaskets and sealed with silicone. The problem continues. I live in northern AZ where I rarely use the AC/HEAT (possibly eliminating a condensation issue). Nor does it precipitate very often (possibly eliminating a leaking hatchback seal). Any ideas?
Do you park the car outside? I’d look at the hatchback seals, water is coming from somewhere and maybe the source of moisture is from the morning dew.