Heater matrix and air con issues

mitchy · Unread post by **mitchy** » 18 Jan 2010, 16:13

Hi all,
I've got a couple of questions regarding heating and air con.

I have a 1999 Xantia 2.0 HDi with air con, I'm happy with it but I'm trying to get my head around the air con and heating.

Firstly the cabin is very damp inside, the windows are almost permanently misty and don't really ever clear. I also get traces of water in the passenger footwell and a smell of coolant in the cabin so I'm pretty sure the heater matrix is leaking. However how does the demist option work? I understand from the hand book that it's not the same as pushing all air to the windscreen vents. Can anyone clarify the above or confirm my worries?

Also when it's on the auto setting it's seems to completely do it's own thing, it will go from blowing out on full to nothing at all then blowing full again.

When on manual it sometimes blows full even when it's not on that setting.

Does all that make sense?

Thanks
Ollie

Unread post by **citroenxm** » 18 Jan 2010, 17:35

Water can also come in if the screen scuttle is NOT glued to the window on the passenger side.

If you have got a leaky matrix, you WILL always get steamy windows, you need to sort the leaky matrix before any proper operating de misting will work.

The fan on auto can be getting dodgy signals from the Cabin Temperture sensor in the dash, and telling the fan to speed up or down to vary the tempeture.. but there could be a few other reasons, I dont know the full electronic side of the system that well to properly advise you.

Paul

Unread post by **CitroJim** » 18 Jan 2010, 18:54

A sure-fire way of checking is to lift the door seal up on the passenger side and slide your hand under the carpet and into the footwell. If your hand comes out wet, either you have a matrix leak or a windscreen scuttle leak.

To determine which, smell and taste. Rainwater may smell a bit musty but will be tasteless by and large. Coolant will have it's characteristic smell and either be very sweet or very bitter to taste. Bitter means it's modern stuff with bittering agents added.

A windscreen leak is easily fixed. Bond the scuttle panel to the screen with a good automotive quality silicone.

The problem is all the damp inside. Only one thing to do, strip the entire interior and dry it out. Takes a couple of weeks this weather...

A duff heater matrix is a LOT of work but try a dose of Forte Stop Leak as a pro-tem fix. Don't use radweld or cheap rad sealers. K-Seal seems to be OK but I'm no fan of it personally; others speak highly of it...