Curing condensation

Best bet is to find the water leak and fix it. When ever I have had this problem in the past it is because something inside is wet and soggy from a leak. (try the boot carpet, the main body carpets or even the thick underfelt below the carpets fitted for sound insulation) Water may be getting in from any one of a multitude of locations.

What car? Make/Model?

Using recirc to circulate damp air is not going to dry it.

Leaving windows partially open is unlikely to achieve anything except disapproval from your insurers.

Unless you spend long periods of time sat in the car when parked, the usual cause of excessive condensation is a leak, as others have said. If this is the case you will never cure the problem until you fix the leak.

A couple of other things to check; does it have a cabin filter? If so, has it been replaced according to the service schedule? A blocked filter will significantly reduce air throughput.

Does it lose coolant? It could have a small leak in the heater matrix.

One last thing; is it a Focus? If so, 'they all do that Sir'...

Chris

is the car fitted with air conditioning? A lot are these days. The benefit of air-con in winter is that it dries the (usually damp) air coming into the cab. If there's air con - use it.

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Thanks to all. Its a 2002 corolla. The cabin filter seems OK to me. I gave it a good tap to loose the dust recently and did wonder at the time if i could (or rather should) use a garden hose to wash it out ) I forgot to mention when I went for the run I used the *air conditioning* (full blast on maximum hot). I'm pretty sure it has no water leaks coming in and is I'm not loosing coolent. I've noticed that the cars in the driveways either side of ours seem to have their windows in pretty much the same state.

No, you should replace it unless you are sure it has been done in the last two years. It's pointless trying anything else until you have done so.

It's essentially made of paper, so washing it with water is not a good idea...

Chris

recuirculating will increase the humidity in the car.

as long as you are in it, breathing.

never use recirculation once the car is warm.

leaving a window open a crack my help a little

Car is parked on north facing side of the house in London. Outside temperature here was about nine degrees midday and dropped down to about two by about eight o'clock in the evening.

In the evening the inside of the car windows were just running with condensation and the whole car inside felt very damp. We wiped the inside windows dry and took the car for a run for about fifteen minutes with the air conditining on maximum heat.

During this drive I used the air vent set to take in the outside air for half the drive and then set it to re-circulate the air, for the rest of the time to dry out the inside of the car.

This morning it's three degrees outside and a lot of wet condensation has re-appeared on the rear window.

Can anything be done to cut down this condensation? I'm toying with the idea of leaving the windows with a very small open gap all the time during this cold weather...would this be a good idea?

Apart from moving to a dry warm country there's not a lot you can do apart from curing any leaks found. Removing anything that will harbour damp other than the carpets, making sure that the aircon is set NOT to recirculate as this only moves the dampness around, and lastly if all else fails sell the car.

I own an SLK ... imagine the fun I have when the "condensation" (aka damp) freezes inside...Live with it for the duration and dry it all out in the summer if you can

My strong suspicion is that there is a leak. Maybe your neighbours have them too. :)

Air holds more moisture when warm than when cold. If you really want to dry the car, you need to run the air con on max coolth, not max heat, preferably whilst not in the car. That should dry out the air nicely. Of course, once you open the door to turn the engine off more damp air will get in.

...snip... Two things that might help you.

Firstly, if it's really just condensation and you don't use the car much, one of those "tablet based" dehumidifiers - although I have to say that mine didn't cope over the last few days.

Secondly, look VERY HARD for leaks. My Zafira sunroof drains became blocked (check by putting a LOT of ware down them and checking that it really is appearing somewhere below the car) and I didn't discover this until the passenger wheelwell was totally full of water. But here's the kicker - because the floorpan is heavily ridged, there is a good 1.5inches of foam in between the floorpan and "carpet where you put your feet" in places. So the carpet appeared dry until I really leaned on it, and a puddle of water appeared.

Paul DS.

Classic sign of a leak somewhere. Get that seen to.

MBQ

blocked plenum chamber on air con? google it

If not and you are convinced that all else is "OK" to dry the car:-

you need to recirc air with air con ON, heat ON FULL for the first part of your drive, THEN switch to NON-recirc air, with the windows open an inch say to get the warm wet air OUT, lastly switch air con OFF BUT heat still ON to dry the pipes of the air system of any condensation that may encourage mould growth, nasty niffs etc.

Jim K

unless the air con is ON.....

Jim K

..and then only if the drain plug is not blocked..

I had an XJS that would spill a pint of icy water on the passengers legs every time on a fast right hander :-)

actually full heat and full aircon is usually the quickest way to dry a car.

If the climate control can be overridden.

plenum chamber drain? i.e. assuming it works? well yers...

yup - what I said.

Jim K

But the air will first be cooled, then warmed.

So there is no more moisture in 'hot' aircon air than in 'cold' aircon air. The relative humidity is lower for the hot air too, so it is better at drying the car.

The air will first be cooled, at which point the moisture condenses and drips out of the aircon unit onto the road, and then warmed

So there is less moisture in the air full stop.

exactly.

You seem confused.

The OP is adamant that there is no leak, and there's no pool of water in the car that needs drying out. Obviously, for drying the car, maximum heat is needed with dry air.

However, the OP is of the opinion that all the condensation on the windows is from the moisture in the air. So, it makes no difference how warm the air is, just the total moisture content.

I may have been wrong about how the air con works. Are you saying that on the maximum heat setting the air is first cooled to the same extent as on the lowest temperature setting? That seems very wasteful, and I assumed (possibly wrongly) that the air con would run at a lower setting if hot air is demanded on the control system than it would for cold air.

All the cars in our road obviously have leaks too, even the brand new Mercs