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-   -   heater blowing cold andwindscreen misting (https://www.the75andztclub.co.uk/forum/showthread.php?t=99473)

fintious maximus 6th December 2011 08:20

heater blowing cold andwindscreen misting
 
Hi all, posting on behalf of my dadand his beloved75 2.0cdti.....

his windscreen mists throughout the year and now cold weather is here the heater won't blow hot air. Also needs air con regassing as doesn't blow really cold in summer.

Any suggestions? Thoughts are possibly heater matrix/thermostat.....

scouseeric 6th December 2011 08:27

Good morning Andy, i think you may need another 'stat fitted in the top hose. Welcome to the club!:xmas-smiley-003:

Eric

Unclefista 6th December 2011 11:58

Quote:

Originally Posted by fintious maximus (Post 868609)
Hi all, posting on behalf of my dadand his beloved75 2.0cdti.....

his windscreen mists throughout the year and now cold weather is here the heater won't blow hot air. Also needs air con regassing as doesn't blow really cold in summer.

Any suggestions? Thoughts are possibly heater matrix/thermostat.....

You need to find out if your thermostat is stuck open, there's a way of displaying the OBD coolant temp on the dash if you have a search, that should tell you whether the thermostat is working.
If the thermostat is fine, next thing I'd look at is coolant level, too low and it doesn't reach the matrix.
After that I'd remove the matrix (easy job) and either replace or clean it out.

All my own opinion, if anyone has anything else to add I'd welcome it :)

kissifer1972 6th December 2011 12:10

Regarding the misting, has anyone checked that his plenums are clear of water?

The misting could be, and usually is, down to the pollen filter being wet from water in the plenum chamber. That needs sorting as a matter of urgency.

It could also be that his radiator fan is not working and therefore not cooling the air con condensor causing his air con to not blow cold. A common fault.

Chris

fintious maximus 6th December 2011 17:43

thanks for the replies guys. Popped round to see him this morning and checked coolant level which was fine. Started her up and after ten or so mins the temp guage had hardly moved from cold - does this point to thermostat?

Also, what and where is the plenum chamber?

kissifer1972 6th December 2011 20:11

Quote:

Originally Posted by fintious maximus (Post 868920)
thanks for the replies guys. Popped round to see him this morning and checked coolant level which was fine. Started her up and after ten or so mins the temp guage had hardly moved from cold - does this point to thermostat?

Also, what and where is the plenum chamber?

Did you have a feel of the pipe to the radiator? Did it feel warm? After tens mins, even with the thermostat open, the temp gauge should have moved off cold, maybe not to 9 O'clock but moved quite a bit. I wonder if the temp sensor is shot?

Anyway the plenums are under the plastic covers at the rear of the engine bay, just in front of the windscreen. The driver's side one is the easiest to check for water through. Unclip it and remove and look for water in the bottom. I would bet there is some in there as, if unchecked, the drains clog up and water builds up in there. Potentially disastrous, as I recently found out, if your ECU gets wet.

Here is a pic of the driver's side plenum cover http://www.ephestione.it/uploads/2011/03/IMAG0742.jpg

Be careful if you have to remove the scuttle panel - the bit that runs along the bottom of the windscreen - as the oval shaped clips that hold it down ping off everywhere - put a little masking tape over each one as one tip I've seen - or have someone who is good at catching handy as you tug it free.

To check the fan with the ignition in position 2 - turn the heater to demist the screen - you should hear the fan run.

HTH

Chris

fintious maximus 7th December 2011 17:35

Temp guage did move a bit to maybe 7 o'clock position.... Didn't feel pipes though.

Anyway today I nipped into Unipart to get a thermostat to give that a try until I discovered that it was £60 (usually pay around a fiver) - it isn't a straight forward part though. So before I spend that much on a 'try' is there anyway of telling that the stat does work?

SD1too 7th December 2011 20:16

Hi Andy,

The 7 o'clock position on the temperature gauge translates to a coolant temperature of 55 degrees. I don't think you'll be wasting your money replacing the thermostat! It's a very common fault on the diesel according to this forum.

Simon.

kissifer1972 7th December 2011 22:47

There is a much cheaper fix than the genuine stat - you can fit one in the top hose - costs about £10

You'll have to have a search on here for details - look for inline stat diesel

see here http://www.the75andztclub.co.uk/foru...ne+stat+diesel

Chris

fintious maximus 8th December 2011 19:10

Thanks for the info thus far. Going to get a proper stat cos me dad likes it that way!

Just had the car in my garage and took the plastic grids off to expose pollen filter which was in about an inch of water and the filter was a black gooey mess. Managed to prod the drain hole and a torrent of water was released so hopefully that will solve the misting up problem.........

Stat on Sunday and then hopefully job done!


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