My wife’s 2003 vw beetle is leaking on the passenger side only. I thought it might be the heater core, but when I checked the water level, it was okay. We have had a lot of rain lately, but it hasn’t leaked until today. I thought it might have leaked through the hatchback or the sun roof, but the sides are dry, and the carpet running up to the back seat is dry as well. The driver’s side is dry. The inside of the car is fogged up. Any ideas?
Possibly a clogged drain from the sunroof. It has four drains so it could be leaking on just the passenger side.
Also I would not rule out a leak in the heater core. Keep watching that coolant level and remember it is possible that it may have leaked some and not yet enough to show a low coolant level.
Add to that list the drain from the vent area in front of the windscreen. It may be clogged with leaves etc so it ends up on the passenger side of the floor.
I’d check the HVAC drain tube first (on the firewall, low on the passenger side), then the sunroof drain in the front passenger corner.
When you stop the leak you may have to remove some of the carpet in order to dry the padding underneath. The padding holds water like a sponge, and is probably responsible for the fogged windows.