it may be the rear light may be cracked or the boot rubber seal. you should also look at a rubber bung that near to bumper level that lets water in too.
I pulled out all the little rubber plugs on the trunk lid. Problemed solved.
my mom's 1991 Chevy lumina always smells musty or "stuffy" and it's because her trunk leaks. just an idea. the leak or source of moisture may not necessarrily be in the passenger compartment.AnswerYou might also want to have your A/C system inspected, specifically the vents/ducts. Mold can grow inside these areas.
A bad trunk seal weatherstrip.
Have you checked the Gasket that goes around the Trunk opening?
I had the same problem with my 1992 Accord. Replacement of the trunk lid gasket fixed the leak, but I had to special order the gasket from a dealer.
A leak.
Bad rubber seal around trunk lid?
It has been damaged or the seal has deteriorated
no. How could you have a leak without a leak? There's a hole in the system somewhere.
Broken or split hose Radiator leak heater core leak
To detect a water leak in a wall, look for signs such as water stains, mold growth, or a musty smell. You can also use a moisture meter or thermal imaging camera to identify the source of the leak. If you suspect a leak, it's important to address it promptly to prevent further damage.
It could be as simple as a vacuum leak but without knowing what year, make, model and engine it is hard to tell you what it may be.