Windows misting up

[rastamon]

Can someone advise me?
Over the last 3 weeks or so my windscreen and the front side windows keep misting up after they have been cleaned. I have cleaned them numerous times with various types of cleaning solutions purchased or homemade(vinegar/water solution) so the glass has been thoroughly degreased. The screen mists up only in parts and highlights the cleaning motion that has taken place. I suspect the air blown on to the glass may contain moisture or oil in it as the glass seems slightly greasy when wiped. My aircon is out of use (no belt)and the setting is on manual upwards arrow. I have an Audi A4 1.9TDI 1998.
Any ideas?

[Col]

Three main things to look into;

1, Check the air distribution is not set to re-circ and also check the re-circ function works (if you have it)

2, Check you pollen filter, a dirty old pollen filter full of dust and debris will remain damp and the it is the dampness that could be pulled through it would cause the windows to mist. Note with the pollen filter out it is easier to check the re-circ function in 1 above.

3, You may have a water ingress problem, check the plenum drains are not blocked and also check the seal around the pollen filter housing.


There is lots of info on all 3 of these on here, do a search.

[cookie1979]

as said above could be pollen filter or blocked drain holes. Or even a loose clip on the plastic surround under windscreen (above the pollen filter).

but sounds more like a leaking heater matrix to me with the 'greasy' residue left on the windows.

Is your passenger footwell damp at all at the very front near the transmition tunnel?

[rastamon]

Many thanks to you both for your advice.
Checked pollen filter - It needs changing.
Car dry inside.
Coolant level had dropped over time but since I have kept a close eye on it
there is not an apparent daily loss.
Drive with temp on low (cold air)- no problem. Increase temp to heat coming out - screen starts to mist.
Suspect small hole in matrix - Radweld added to coolant - Car left running on 26C - no misting up.
Proof tomorrow - colder in morning on journey to work.
Out of interest, I suspect changing matrix is a long job (getting at it).
Anyone done it? How long?

Thanks again.