Heater - screen demisting, is it normal?

[salty_monk]

I know a lot of you use the quarter lights for demisting but my girlfriend uses it on a daily basis & she gets cold...

My question is this; the heater works really well & gets hot pretty quickly (it's a 68, 2 door) & has the latest model heater with ram air pipe, electric fan & selector.

The electric fan also works well but is not necessary at any speed as the air ram overtakes it....

So...get to the point.. when changing the selector between car & screen it makes little difference so is this normal or is it me?

In the "car" position you get almost no air through the dash vents, in screen you get very little air through the dash vents.

From memory turning selector to off also makes little difference, is there a deflector plate or something in there that could be dis-connected?

Also the fan makes a loud screech on start up but settles within a second or so to a fairly quiet rattle, are the bearing on their way out? ARe they easy to get to?

Cheers,

Dan

[Willie]

It is quite common for the concertina tubes which connect
to the de misting vents to become detached, meaning that you
do not get a nice flow of air to the screen. Have a check.

[Cam]

Actually the screech, and lack of direction of the air sounds VERY familiar to me! you are not alone...................

[salty_monk]

HMM. Might have to undo some bolts in the near future for a look then. The tubes all "seem" to be connected as far as I can tell from a grope around under there blind...
I guess the matrix could probably with being reverse flushed anyhow.... Just weird how the "car" bit works so well & the direction of flow doesn't.... I'll let you know if I find anything out. Could be time to have a scan of the manuals!

[MrA.Series]

So...get to the point.. when changing the selector between car & screen it makes little difference so is this normal or is it me?

In the "car" position you get almost no air through the dash vents, in screen you get very little air through the dash vents.

From memory turning selector to off also makes little difference, is there a deflector plate or something in there that could be dis-connected?

Also the fan makes a loud screech on start up but settles within a second or so to a fairly quiet rattle, are the bearing on their way out? ARe they easy to get to?

Right,
Here is the full proper way the SII/1000 heater selector works.

~#~ In OFF mode, the deflector plate (connected to the selector handle inside the heater) should block off all incoming air. [Note: The foam edgeing on the deflector can get damaged if old and degrading if the fan is switched ON when in this mode, which causes the selector to not be a good seal, hence leaking air out of unwanted vents.]

~#~ In SCREEN mode, the deflector is slid back a notch to reveil the air exits, to the screen vents, to the incoming flow of air. Air should only be coming out of your screen vents in this mode. [Note: Might not be the case due to damaged foam on deflector. See the above Note].

~#~ In CAR mode, the deflector plate is slid right back revileing the car exits to the car vents (either side of heater to foot wells and the slit in the front of the heater) and the already revield screen exits for the Screen vents on the dash. Air should come out of all vents; both car and screen vents, but due to the loss in pressure because of more vents being fed by the incoming air, the air from the screen vents comes out less powerful (should be about a powerfull as the air coimng out of the foot well vents).
[Note: The front slit 'car' vent in the heater will always come out a bit more powerful than any other of the 5 vents in CAR mode as it has a very short distance to flow from the heater, thus better flow capabilities!]

Hope that helps,

Rob

(PS: Reached the 100 post mark with this post! Yay! And what a post, eh? My fingers are currently now dead!)

[rayofleamington]

salty_monk,
My present everyday(ish) Minor is exaclty the same as yours. However it isn't right. As described by Rob, there should be almost no flow to the car when in screen position.
I wedge the lever about half an inch closer to off than the latch position and this reduces the flow into the car, yet it still takes a long long time before the screen is cleared by the air flow alone.

[MrA.Series]

Rob, there should be almost no flow to the car when in screen position.

Thats what I said!

"Air should only be coming out of your screen vents in this mode"

[salty_monk]

Ok, don't argue I get the picture..

The long & the short is mine's not right & it has to be something to do with the deflector plate and/or foam from your comments.

Thanks for all your help, I shall attack it with my very best spanner soon (once I've changed the oil & filter & finished hammeriting everything in site that dares to show any rust!)

[MrA.Series]

All oppologies ray, I miss-read what you said. Guess who feels like the biggest fool in the world right now!

[rayofleamington]

I miss-read what you said.

probably because I missed a full stop out - sneaked it back in to make you feel bad ;-)
seems like it worked! lol

[MrA.Series]

Hey! I thought It sounded diffrent in my head the second time I read it! Oh well, we're as bad as each other!

[PaulJohnson]

Actually the screech, and lack of direction of the air sounds VERY familiar to me! you are not alone...................

I had the same problem so I got the Moggy garage in Manchester to fit (Olive) a new demister motor (No problems now)
Also if you would like more Air on your windscreen see my post in the Useful Tips section.

Best Wishes Paul

[Matt]

I get a screach, but the deflector seems to work quite well, would the screach be worn bearings in the motor?

[Matt]

you mean someone might have put a mouse in my motor rather than bearings????

[Kevin]

I wonder how many with the later type original heaters dont screech on start up I always thought it was a standard feature.

[alainmoran]

Has anyone ever thought of disconnecting/blocking the inlet pipe from the front of the car, the idea being to recirculate the air rather than heat fresh-air all the time, after all the minor has enough draughts and that to ensure that the air doesnt get too stale, and it might make the car a little warmer on longer runs.

I havent yet tried this out, its an idea which came to me while freezing my bits off driving down the M6 over christmass, and I've been too busy with Audrey to try it out!

[Peetee]

That would work if there was somewhere else for the air to enter the heater. It doesn't work too well however if the inside is damp (from the wet occupants/whatever) as demisting will be non-existant.

[rayofleamington]

the earlier heaters have a flap to control exterior or interior air.
Yes I've often wondered the same, whilst shivering on a long Motorway journey!

[Willie]

My '57 heater has NO air inlet at all, as was normal then.
It is totally re-circulatory. I have cleaned it out with the
kettle descaler which improved the heat output,but not to
a very good standard. I have just re-read the workshop
manual on fitting the recirculatory heater and it states that
"the 74 degree thermostat should be replaced by the 80 to
85 degree item". When I checked my thermostat it was a
74 degree one so I have replaced it pronto with the higher
rated one.....not a startling improvement but worthwhile.