S60 - Condensation in rear Windshield - Water Accumulation Trunk Lid

[ionianp2]

Hi Everyone,

I hope everyone had a good weekend. I was wondering if someone could shed some light on where to troubleshoot an odd issue, on a '04 S60. I am noticing condensation on the rear windshield while parked, when all other cars next to me don't have it. I initially thought it might have been a heater core leak but I am not seeing any condensation on any other windows, nor the front windshield. I also looked underneath the carpet of the driver and front passenger side and I see no coolant leaks. I also felt the parcel shelf trim/carpet, and it seems fairly dry (not drenched).

I am seeing water accumulation in the trunk lid and the fuzzy trim piece is damp. I removed it for now to see if things dry out. I don't have a sunroof, therefore no drain tubes, so I'm wondering where could this moisture come from?

Any pointers on where to look would be greatly appreciated.

Best Regards,

IonianP2

[oragex]

Even if you don't have the sunroof, may also want to slide a hand under under the front pass carpet, careful because it tears quite easily. Leaks may come from the cabin blower, cabin air filter cover, AC drain, etc

I would not recommend the following if you have exhaust leaks, or if the trunk battery is missing the small vent hose
May try remove the deck cover, and you'll find a sound proof material underneath. I did cut a piece of this material right in the middle, so the grid on the cover is now communicating with the trunk - there are vents on the sides of the trunk so the airflow goes outside. This may create the airflow needed to clear that windshield frost. Originally, the grid on the cover is actually a fake one, just for the looks. Few things: this will allow fumes from the exhaust to pass from the trunk inside the cabin, so a safety hazard. Also, the battery is located inside the trunk and can vent toxic gas which may also find their way inside the cabin (normally the battery has a vent hose to it). The deck cover is annoying to remove and to put back, and may start rattle, see link below for 'rear deck removal'

[csh]

Another thing ti check is to open the trunk and check around the seal to make sure that there isn't excess junk accumulated around the seal. That can create a dam and when it rains excess water can build up behind that dam and run down into the trunk. There are vent openings between the trunk and the cabin and the rear hat shelf(deck) so moisture in the trunk could lead to fogging of the rear window. Something easy to check and resolve if that is the problem.

[motormikeyman]

As noted above, you probably have a water leak in the trunk. In my case, this was caused by a few half empty water bottles rolling around slowly leaking. Check your spare tire well for water. You can search for the leak by crawling in the trunk with a flashlight and having someone douse the back of the car with a hose (as silly as that sounds).

[ndphotonl]

Probably also the only way