R172/SLK Condensation, water drains

[reflexboy]

I appreciate the weather has changed for the worse now, but the condensation in my partner's SLK (R172) is really bad. The carpets, foot wells and boot are all bone dry and the pollen filter is also bone dry. The outlet drain from the pollen filter box is clear also. When putting the Thermotronic to the max setting to clear the windscreen it takes an age. The condensation is literally running down the inside of the windscreen. The AC seems to work OK and I have cleaned and treated all the door, roof and boot seals. Is there anything else I need to check? Is there a guide to checking and locating where the water drains are on an R172, or is this just a 'trait' of the car?

 

[Piff]

check that it is not set on recirculate

 

[reflexboy]

check that it is not set on recirculate

it's not. When it's on max/windscreen the recirculate is off anyway

 

[leef44]

How puzzling

Have you checked the drain channel at the back of the bonnet where the windscreen wipers are?

Small twigs/leaves and such things can get blocked there. If so, there might be a build up of water or a wet blockage.

 

[reflexboy]

How puzzling Have you checked the drain channel at the back of the bonnet where the windscreen wipers are? Small twigs/leaves and such things can get blocked there. If so, there might be a build up of water or a wet blockage.

will do and thank you

 

[Erfan]

Prior to when the car is locked its an idea to air it (leave door open for a bit) or open window on last part of journey. If the heaters are being used this will help equalise the cabin temp with outside temp and hopefully reduce condesation.

 

[Piff]

hmmm, in 3 years of ownership never experienced this

 

[reflexboy]

hmmm, in 3 years of ownership never experienced this

was your car garaged or did it live outside?

 

[Dec]

Sounds like the AC is not working properly or is not being used all the time.
Does the car get used daily?

Dec

 

[reflexboy]

Sounds like the AC is not working properly or is not being used all the time. Does the car get used daily? Dec

it is used daily. Obviously not the weather for it but the AC does get nice and cold. I have checked everything I can think of, so am a bit stumped. Parked it in the garage last night and no condensation so maybe it's just me being a bit OCD and the cause is the damp weather

 

[Dec]

You can use the AC while the heater is on hot. Some people use the AC only on hot summer days but it is intended to be used all year round. Maybe it just needs re-gassing.

Dec

 

[Piff]

was your car garaged or did it live outside?

Lived outside. SWMBO often parked under tress at work when no other spaces available. Occasionally had to pick a few leaves out at the base of the windscreen.

 

[Piff]

I also have AC (climate control) on all year round - just set a temperature & let the car/truck work out how to achieve it.

 

[reflexboy]

Yup, we just leave it on 'Auto' and let the car do the rest. Just out of curiosity, when I press the 'windscreen Max' button all other climate control lights go out, inc. the AC light...is this correct?

 

[Dec]

I wouldn’t know about all the AC lights going out when windscreen max button is pressed but I think 'windscreen Max' probably is to clear/defrost the windscreen and side windows as quickly as possible and maybe self cancels after a set time. The user manual would need to be studied to see what it says about that.

The auto setting regulates the air direction and the temperature of the air coming out of the vents, you can have it set to auto AND have the AC OFF or have the AC ON. So, you should really have the AC light on all the time.

When the is AC, on, the light on the button is on so you are getting dehumanised air through the vents, when AC is off then the AC light is off and any condensation is slow to clear because of the absence of dry air.

Dec

 

[GP801]

Yup, we just leave it on 'Auto' and let the car do the rest. Just out of curiosity, when I press the 'windscreen Max' button all other climate control lights go out, inc. the AC light...is this correct?

Yes. For some reason it is set up so that no AC when on max demist. Our SLK is a 171 but for some reason every so often it just gets dripping in water even set to auto with AC on. MB can find nothing wrong with it. Some suggest its the front SAM unit causing the compressor to stop for a time. Not sure if its relevant to the 172 but I don't think there is lot of difference in the set up

 

[BPD07]

On my old R170, it suffered condensation like you're saying. No obvious water ingress, but I noted that the rubber stoppers on the front of the booted (nearest the rear glass) were making the lid slightly proud. A turn or two on the bolts on both sides and it sat lower. No more condensation.

 

[w4rp]

To OP, the box that holds the R172 battery can fill with water.

If it does, the water will overflow into the car and on to the heater fan/blower as the box is also the air intake for the heater/aircon system.

The drain is at the very front of the battery in the middle, you will be able to find it with your finger. Sticking your finger down it will probably unblock it.

You only need to lift the bonnet and take the lid of the battery box to check.

Hope this helps

 

[steve333]

I appreciate the weather has changed for the worse now, but the condensation in my partner's SLK (R172) is really bad. The carpets, foot wells and boot are all bone dry and the pollen filter is also bone dry. The outlet drain from the pollen filter box is clear also. When putting the Thermotronic to the max setting to clear the windscreen it takes an age. The condensation is literally running down the inside of the windscreen. The AC seems to work OK and I have cleaned and treated all the door, roof and boot seals. Is there anything else I need to check? Is there a guide to checking and locating where the water drains are on an R172, or is this just a 'trait' of the car?

My wife's is an r171 but here's what works on her car when condensation forms inside during cold snaps-after drying properly(heater and fan on max) drive the car with the roof down(make use of those lovely heated seats and airscarf if you have one) and then when parked and roof up leaves windows slightly opened for some time,hope that helps!

 

[reflexboy]

To OP, the box that holds the R172 battery can fill with water.

If it does, the water will overflow into the car and on to the heater fan/blower as the box is also the air intake for the heater/aircon system.

The drain is at the very front of the battery in the middle, you will be able to find it with your finger. Sticking your finger down it will probably unblock it.

You only need to lift the bonnet and take the lid of the battery box to check.

Hope this helps

Thank you-I will check that at the weekend.