Interior Windows Misting Up - Where are ALL the water drains ?

Hello,

As per Subject I have noticed that since the weather has got noticeably colder & wetter here in Norfolk, UK. My car has started to mist up a bit, it was fine during the summer.

My car: 2007 , NC Coupe, with power folding hard top.

This morning was the first proper hard frost and I had frost/ice inside and outside all of the windows.

Once it has cleared everything is fine, especially with Heating and Air Con switched on. 

I have also noticed that the Windscreen doesn’t de-mist the LH Passenger side of the Windscreen as well as the RH Drivers side, I assume a loose Hose/ Gasper outlet, or maybe a sticky flap/valve inside the air distribution box ?

A couple of the buttons have also stuck open in the gasper outlets, is this a common problem ?

The car is used at least 2-3 days per week, for 80-120 miles total commuting.

 

Is there a comprehensive list of all of the Body water drains I should inspect. I have a long flexi Trombone Brush and have cleared out the drains behind the seats in the space where the Hood folds into.

Of course it’s a common problem, they don’t actually close by design, dimwit !

Answered one of my own Q’s, whilst researching how to take the dash apart, this forum is a mine of information…

Simple question first, have you got it in air recirculation mode? It needs to pull air from the outside for a more efficient demist operation. Still could be a flap stuck somewhere preventing the air distribution.

No, I drive in ‘outside air’ mode 99% of the time. I occasionally use recirculation to warm the inside a bit quicker on a cold morning, or cool it down on a really hot day, but only use it for a few minutes.

I reckon I have a bit of moisture inside because of a blocked drain, or water ingress. The rubber seals all looked in good nick last time i cleaned them all, with no obvious rips or tears. 

 

The front grommets leak, as in this thread below, so check if you have a damp footwell.

https://www.mx5oc.co.uk/forum/yaf_postst116969_Water-in-passenger-footwell.aspx

I have exactly the same problem with my 2010 PRHT. The rear drains are clear and there’s no sign of damp in any of the carpets. I even had a look down behind the glovebox for telltale signs but nothing obvious. I had to wipe the front screen as the demister wouldn’t cut it and it soaked 2 pieces of kitchen roll.

I don’t remember it being a problem last year and the only thing that’s changed has been a dashcam fitted by Halfords, and the Dinitrol treatment 2 weeks ago.

Same with mine a little patch on the front LH screen that takes longer to clear and noticed when I look in the rear view mirror the rear left takes longer to clear as if the blower is not  has strong on the left …bone dry everywhere 

Anyone in S Yorks area willing to walk a complete DIY liability through changing the grommets or should I just whip it in to MX5 City ?

I’ve st had a good prod around with a Lidl damp meter (other brands are available).

Passenger carpet is dry and not registering anything on the meter.

In the boot under the carpet, the white felt backing has a couple of damp spots, probably no more than 2” square each. These measure >1%.

- I’ve had to open the boot when it’s been chucking down recently so not sure if it’s residual or ingress from elsewhere.

There are small patches just after the plastic rear panels behind the seats that are measuring around 0.7%.

- could be just condensation that’s formed between the panels and bodywork as the drains are clear (it’s a PRHT) ?

Finally, I put a big silica condensation trap in the car overnight on the console between the seats and this reads 0%

Starting to get flummoxed now.   could the Dinitrol treatment have exacerbated the condensation forming ?

My car suffers more from condensation in the Winter.The drains are clear. I put it down to the colder weather and increased rain. Damp coats bring moisture into the interior of the car and the warm air in the car, once the heater has warmed up, soaks up the moisture. Overnight the moisture in the warm air cools and condenses on the cold glass. Simple physics. The same reason we get more dew or frost on the car overnight in the Winter.

Driving with the heater off and the windows open will allow the air in the car to stabilize but any moisture will still condense overnight.

Check cill drains, 2 each side, roughly where jacking points are.
Only about 25 mm long,1mm wide.
A mirror and something like a cocktail stick works for me.

Same was happening to my mk3.75  last month after a service and air con refill then remembered I had a new window screen fitted earlier in the year.  I took off the wiper arms and front plastic cover and found the white plastic screw blocks were loose in the silicone I had added some years ago.  Brought 2 new blocks and resealed them.  I have had no problems since.

Graham

In the boot each side behind the bumper and below the lights are ventilation exits protected by a rubber flap.  It is possible these might have become stuck shut, or much worse are missing.

If stuck shut then the boot is not ventilated, and probably not much in the cabin either resulting in condensation; we breathe out moisture, and our clothes if damp will also steam away.

If missing then the opportunity exists for blow back of rain into the boot, most likely when parked backing into the wind or during washing.

With the lid and windows closed there should still be a strong draft through the heater system when it is on full.

My NC climate control demists much more quickly than does the newer Mazda3 with its supposedly much cleverer climate control.

We leave the aircon enabled all year round on both cars, it only switches on when really needed.

On another point with condensation does anyone get the square patches on the body work pefectly patterned on the PRHT and what is it…

I think it’s just down to the very damp weather spell. We have a boat with a canvas canopy and this late Autumn even though the boat is bone dry inside the moisture inside under the canopy is the worst i and many boating friends have seen it. Our NC is only a high day car and this autumn notice a bit more condensation inside some mornings, checked the usual suspects but all dry so i just put a silica moisture trap inside and been ok since. 

You could also make sure the door drain holes are clear although if blocked you would most likely hear water sloshing about in them.

My daily driver is checked regularly for door drain holes blocked. The earlier models (it’s a SEAT)  had reported water retention in the rear doors, some in the front doors too. A simple process of poking the drain holes clear and making sure that the rubber door seal hadn’t stuck to the door over the drain hole. The cause of this blockage was wax oozing from the drain holes from the door cavity, some even cut a V shape in the seal to aide drainage.

I don’t think the Mazdas suffer this above but worth checking. I clean my door seals along the botton of the doors regularly and was surprised the from first time how much crud had built up there over the years previous to my ownership.

I think I’ve solved most of my issue now. I constructed a pipe and funnel arrangement and the passengers side wasn’t draining as fast as the flow, whereas the drivers side did. I spoke to MX5 City and called in but they suggested it’d be a couple of hours labour to remove the trim to get to the drain so I used the pressure washer with an angled attachment and the drain is now clear. Nothing other than water came out, or at least if it did it was blown to bits by the pressure, so I’m suspecting that some of the Dinitrol wax caught the drain flap and stopped it opening fully under the weight of the water.

I’ve still got some damp on the rear edge of the boot mat so I’ll have a look for the vents mentioned by Richard.

The pattern on the PRHT is just how cold spots follow the seams or insulation depending on how it’s constructed. Had the same on my previous folding lids so nothing to worry about.

Apologies for droning on, but I’m happy that I’ve solved the drainage for the roof but it’s induced the dreaded wheel bearing noise. I’m planning to leave it until warmer weather to investigate further as I’d sooner be dry than quiet.

Is it likely I’ve messed something up with the Karcher ? I gave it pretty short pulses as I didn’t want to flood the roof compartment but I have no idea what the internal structure is. Does it contain foam ?

 

You may have dislodged the baffle in the drain pipe, on the Mk3 it sits near the bottom of the outlet that exits under the car just forward of the wheel. It sounds like bearing noise more like road noise coming into the cabin.