went for a drive tonight (haven't driven it for a week :)), anyway i noticed that the drivers side floor and passengers side floor was damp (driving with no shoes). pulled back the carpet and it was a bit damp, had a quick look up under the dash. couldn't see much, the ecu wasn't wet or anything(has a plastic bag on it just in case). The water on the floor wasn't green or anything, i noticed that the leaf guard near the wipers are starting to deteriorate, would this be the cause or is it the common heater core. if its the heater core then it gives me an excuse to do a climate control conversion.

I would think heater core, but if your coolant is nice and green then maybe not. If it was on both sides it suggests a central leak rather than a corner seal etc.

I had a leak under the passenger guard/down behind the glovebox and the whole carpet ended up wet. Has it rained on your car recently? Get the hose out or give it a wash and see if the carpet gets very wet anywhere. If it does, its probably a bodywork leak. Leaf guards deteriorating shouldn't make it leak, there is a trough under them that drains out the edges, and where the air for the fan comes in is raised with another plastic guard over it to keep the water out.

How is the state of the rubber trim at the bottom of the front windscreen? As Timi stated, best to get a hose and water the car to see if any water gets in. Also, on the topic of the plastic over the ECU. It is a bad design, especially if the heater core leak develops in winter as warm moist air will actually condense on the underside of the plastic and then drop right onto the ECU. This has happened to a few people I know. Best to make sure the plastic is taught or better yet, raised at the centre so water droplets don't fall over the ecu.

windscreen leak?

http://www.picturestack.com/760/712/xuh001pE8.th.jpg (http://www.picturestack.com/760/712/xuh001pE8.jpg)
Top left corner of where all the black goop is. If you think you have found the leak, tape it up or fill it with plasticene and double-check before you glue guards down or replace a windscreen and still have a leak...

update time,

took the trims off and pored some water down in the windscreen valley, had a look under the dash and no leak :grrr:. so ill pull the guard of tomorrow and have a look see

I had a leak on the passengers side of my car, turned out to be a rubber grommet in the firewall, which was cut and not seated correctly.

Easiest way to descibe its location, open pass door, in foorwell, behind the dash - look up to the top of the carpet.
there is a rubber grommet to the side - towards the A pillar.
The other side of this - is behind the Wheel arch Liner - and if its like a KL - there is a hole in the wheel arch liner... that lines up with this grommet.

Its actually water spray / mist that is being thrown up by the tyres - hitting the wheel arch liner - going through the hole - and then finding the grommet that is broken.
it becomes a constant stream of mist into the car, that then runs down the metal and comes up from under the carpet.

Had a couple of the mackay guys cars do that - each time, turned out to be that grommet.

That grommet was leaking in mine too when I poured water down the firewall, there were no leaks pouring water in the channel under the leaf guards around the airbox, but if I poured it down the pass. side of the windscreen from about halfway up, it would run down the pillar and through that leak under the guard. When I sealed it up I also pushed a piece of garden hose through that came out lower down the cr near the indicator, and sealed around that incase it was supposed to be a gutter/drain hole near the leak.

Blocked A/C drain causing condensation?

window seals maybe,is there any rust it could be getting in through there

Mal can quote me on this, I have the same leak on the passenger side

So far i have:
Replaced the windscreen
Replaced the heater core
Replaced the leaf guards
Washed out the leaves and gunk from the RHS of the fan intake (used hose as cannot see in)
and sealed up every bung and weld i could with sealant.

The car still leaks but not as much as it used to.

Mal and I have put it down to rust and gunk eating away beside the fan intake or where the passenger side door is attached to the car...

hi , i can understand the frustration. I had moisture and wet carpet on passenger side for a while and went through all the possibilities. It was rather obvious however that the rubber door and window seal was more "worn" for some reason on that side of the car to the other. I replaced it and so far no moisture and no leak after downpours and car washes.Problem is its a lot of rubber and goes all the way to back doors as well.$$$$$

Get the hose out and pull the carpet back, and work your way bottom to top to see how far up you go before it starts to leak, if it starts just as you go over the top of the guard, take it off and repeat bottom to top on the inside of where the guard was.
edit: have someone in the car with a torch to tell you when they see the water.