Water getting in behind blower motor - HELP!

[RolfGolf]

Okay - I pulled the thermal fuse holder and the blower motor out (in response to my AC not working) to find a pool of water behind the blower motor ... Not good!

I removed the access tray to the cabin pollen filter to check where the water was coming from and noticed part of the cabin pollen filter was wet so I prised up the plastic rain tray a bit to get a better view and I could see water running down the metal bit shown in the photo and dripping off over the cabin pollen filter.

Is this routed somewhere by the tray that covers the pollen filter or could it be the leak I'm tracing?

The windscreen was replaced a fair few years ago now, but given the state of the thermal fuse enclosure it looks like water has been accumulating for some time ... Would a leak at the base of the windscreen send water into this area?

Occasionally the carpet on the passenger side has been wet and I've been unable to suss out where its coming from. I don't have a sunroof so that's out of the question ... Any ideas? Could it be the windscreen wasn't sealed properly and the water is making its way in through that - the lining behind the pollen filter and under the windscreen is wet ...

[The One]

Warranty on windscreen? Get your car water tested mate.

[RolfGolf]

Cheers for the reply.

Yes, I think a water test is necessary - it's definitely getting in through the cabin pollen filter as when I reach up through the plastic tube that leads to the blower motor, it's all wet in there.

[The One]

There obviously is ducting in that area (through the plenum chamber to get to the pollen filter and then through the pollen to the blower motor) if waters is building up on the plenum chamber (normal) but passing onto the pollen filter (also somewhat normal) it should drain off through one of the guards to under and away from the car, best be checking all your 'covers'/chambers around the pollen filter housing and that general area for any cracks or obvious signs of damage etc. I fear these replacement parts will most likely be ex Germany and not cheap if found to be at fault.

[The One]

Been awhile since I've touched a MK4, so don't take my advice as gospel haha.

[RolfGolf]

Been awhile since I've touched a MK4, so don't take my advice as gospel haha.

Thanks for replying. Gives me some starting points - we've apparently got four days of rain coming up so I need to find somewhere dry to really go over the front windscreen area and all the drains ... (on a positive note, water testing should be a piece of cake as I only need to leave the car in the rain for a couple of minutes and the problem starts up again!)

[grtuned]

Make sure that the plenum cover is sitting flush when you put it back. A lot of dirt builds up in the channel which is part of the windscreen. Use a screwdriver and gently remove any dirt in that channel. When reinstalling the pollen filter make sure the cover which screws into the plenum cover has no cracks in it this aids in water drainage and stops water from getting onto the pollen filter.
Also check the sides of the plenum and make sure there not blocked. Another thing is if you haven't removed your inner guard lining on the front wheel arches over time a build up of leaves and dirt accumulates which causes drainage issues have a look there not difficult to remove.
I don't think your screen is leaking as the plenum cover fits over the point were the sealant for the screen is, which is lower then the plenum cover. If it was coming from the top you would have water running in the inside of the screen.

[RolfGolf]

Make sure that the plenum cover is sitting flush when you put it back. A lot of dirt builds up in the channel which is part of the windscreen. Use a screwdriver and gently remove any dirt in that channel. When reinstalling the pollen filter make sure the cover which screws into the plenum cover has no cracks in it this aids in water drainage and stops water from getting onto the pollen filter.
Also check the sides of the plenum and make sure there not blocked. Another thing is if you haven't removed your inner guard lining on the front wheel arches over time a build up of leaves and dirt accumulates which causes drainage issues have a look there not difficult to remove.
I don't think your screen is leaking as the plenum cover fits over the point were the sealant for the screen is, which is lower then the plenum cover. If it was coming from the top you would have water running in the inside of the screen.

Good thoughts re. the plenum cover.

I noticed yesterday that the "funky" shape of my plenum cover was not OEM. Seems to have had a bit of force applied to it that broke a chunk out the back of it at some stage (made it easy to get in and out but has allowed water to run down through the filter over time) ... I went to Volksfactory today and managed to source one off a car Paul is wrecking. It's raining pretty heavily now so I'll check in the morning whether there's water inside the ducting to the blower motor.

Tried to get the windscreen cowl off to check out what's going on in the rain tray but was thwarted by the windscreen wipers - I replaced those last year and I did a good job attaching them(!) Tried a battery terminal puller in the end but still couldn't budge either one. I'll soak them with WD40 if the rain eases up enough tomorrow and have another go.

I've done the lower guard linings a couple of times now, but they are probably due again as I get a lot of leaf debris washed down behind there.

Good point re. the windscreen too - I think you're probably correct in saying it's not leaking and now that I know water has been getting down to the blower motor through the ducting, it could explain the problems I've had with the windscreen fogging up a lot in Winter.

Hopefully cleaning out all the water drains, behind the wheel arch linings, raintray and replacing the plenum cover will fix things.

Ordered a new voltage regulator/thermal fuse assembly as mine is well and truly shagged (I had to cut it out as part of the wiring had melted the plastic of the connector into the housing) also grabbed a connector and some wire from the same wreck today so maybe a small victory!

Cheers.

[RolfGolf]

Update on this:

Checked behind the blower motor this morning and it appears to be dry - will keep an eye on it over the next couple of days, but it looks like the plenum cover may have been the culprit. It's something worth checking on all Mk4's as the wreck I looked at yesterday had the same kind of issue with the voltage regulator/thermal fuse assembly. (picture 3 above)