Another condensation question

[Chippychap]

Hi Guys, I've seen postings about condensation in cars first thing in the morning.
My W169 is fine until I start driving.
When in traffic the windows tend to mist up.
I can clear it with a 30 second blast on full power, fan that is, not the car.
I tend to turn off the air-con as it seems that if the temp control is above cold then the car is fighting agin itself, heater trying to heat up and A/C tring to cool it down.
What am I doing wrong?

 

[fuzzer]

Just set the temp dials to the white section and leave them there. Unless there is a fault the car wont fight againsed itself.

If youve got an auto button use it , if not control the fan speed yourself.

Running the air con will keep your car from steaming up and it goes without saying that the fan should always be on.

 

[Chippychap]

The controls I have are....
3 rotary switches
On the left a temp dial from 18ish to 30ish
Centre is the fan with defrost as number 5, which is the only fan setting which you can hear and is like fan on full.
Right hand one is the distribution switch, feet and face etc.
One button below just says "Air-con off" which I am using at present.
So, it seems that you just set temp you need but not sure where air-con fits into this system.
the fan is weird as, on my other cars you could hear an increase in noise and felt blow as the fan was altered. On this we go from 1 to 4 with no discernible change then "5" is blow the feathers off a duck setting.
It doesn't seem to rise in stages.

 

[elpeterol]

Just set the temperature to about 20 and leave the aircon on, it dries the air coming into the car. The fan can be left on 1 or 2 unless the windscreen is icy. My A class steams up very slighltly at first but clears in seconds.

 

[Ted]

As others have said - the aircon SHOULD be on. One isn't fighting the other - it is designed to work that way as it dries the air coming into the vehicle.

 

[Carrotchomper]

Sounds like the variable resistor in the fan might be going? But yes, as the others say, keep the aircon on!

 

[MangoMan]

Just a couple of points I would like to make if I may.

Initially my thought is, is that your fan switch (rheostat) is faulty, I di have this on a Merc before, was an older one agreed, with markings, (I II III III) the fan only worked on (III), none of the others.

Secondly, when you use the A/C, ice forms on the condensor, yes, believe it or not it does, this is why after you have used it a lot when it's hot a puddle forms under the car when you have left it for some time, this is the ice melting and going down a drain to the outside. Anyway, getting back, this still happens (with the A/C on) even with the heat on to a certain degree, so when you use it in short bursts as you say, insteaf of the ice melting and draining, it is evaporating and coming into the Cabin, thus causing Condensation on the cold surfaces inside you car when it cools again.

Therefore I would suggest, one, get you rheostat checked, and if that is ok, I would either use the A/C all the time until well after the interior of you car has warmed, or do not use it in the manner you have been.

Also, if you do use the A/C for long periods, but not in hot weather, turn it off a few minutes before the end of your journey to dissipate the ice and condensation inside the car before you stop, otherwise this will just stay in your car as moisture, and will get into your upholstery, etc.

Cheers, Bill.

 

[steptoe]

Aircon dehumidifies the air. So leave it on.

 

[fuzzer]

i would also change the pollen filter

 

[219]

One good reason for NOT using the air con is that it increaese the fuel consumption of your car - I'm not sure by how much , but on my W126 there is a significant additional loading on the engine when the compressor engages , almost akin to moving the gear selector from N to D !

Only you can decide how important this additional running cost is to you .

 

[Chippychap]

Thanks guys and I take everything on board.
I don't keep turning the A/C on and off, I keep using the number 5 on the fan switch. But it does go from can't feel or hear a thing to Mig jet.
30 seconds on 5 clears the windows.screen but in traffic, slower speeds, bring it right back again.
Where would I find the rheostat doodah?
Pollen filter is dead easy, hopefully, on this.
You have given me much more understanding of what is happening in there.
Thank you.

 

[MangoMan]

Where would I find the rheostat doodah?

On the other side of the knob for adjusting the Fan, behind the dash.

Ciao.

NB. I was just looking at some sites, and by the looks of it, it looks like that is one complete system with the three switches. I would get it checked at a Dealer though, I could be wrong.

 

[Chippychap]

On the other side of the knob for adjusting the Fan, behind the dash.

Ciao.

NB. I was just looking at some sites, and by the looks of it, it looks like that is one complete system with the three switches. I would get it checked at a Dealer though, I could be wrong.

Thank you.

Ken