75ZT Community

On my CDT I am not impressed with the demisting performance. My old 418 Diesel used to demist the screen and front door windowsvery quickly,the air used to be very warm/ hot. On my 75 the demist air just seems luke warm and the windscreen takes a very long to clear.
Is this a symptom of a blocked heater matrix?

I have found with my CDT that if I turn down my Temp to 20 / 22 Degrees, it warms up quicker. I have the Inline Stat Mod which helps too.

Not too sure on the slow demist, mine isn't as quick to demist as the Petrol model I had previously, but is still respectable enough to get off the Drive in under 5 minutes.

I find running the car with air con on keeps the screen clear,
and of course the front demist switch soon clears the screen.
Those with FBH (Fuel burning heater.) fitted to their Diesel cars don't suffer this either,
a retrofit can be done but is expensive.

I have an FBH but not sure if it works, have no remote for it etc.

carlpenn wrote:I have an FBH but not sure if it works, have no remote for it etc.

Hi Carl it should kick in itself if its below 5c i think or there is a test you can do ned to find the post hold on but you will have to swap over channels
http://www.the75andztclub.co.uk/forum/s ... post877768

The other morning all of the windows were frosted and the 75 was only defrosted by about a quarter of the window area but a Vauxhall Astra became totally defrosted in the same time. The Astra window vents were blowing hot air but the 75 was only lukewarm. Makes me think the 75 has a problem. The 75 does not have a FBH.

Rover418275 wrote:The 75 does not have a FBH.

This will be the culprit, Mike. Without the support of a FBH it will take ages for the engine to get warm in freezing temperatures. So for long you won't get enough heat to defrost the windows, if the car wasn't parked inside a garage.

Ta Jürgen, even today (7.5 degrees C) the door vents only blew luke warm air, my old 418SLD would defrosted a frozen turkey in no time at all.

Mike

Well, Mike, above 5°C the FBH doesn't matter anyway. But the A/C should quicken the demisting process as it's drying the air. Two things come to my mind, a wet pollen filter or a broken thermostat. The latter will prevent the engine from getting warm. On mine the temperature gauge never reached its normal medium position with this fault. But I didn't suffer from heavily misted windows.

You can easily test what the heater is doing by :- set the knurled knob below the clock to the extreme left position, start engine, turn on the ATC (Automatic Temperature Control), set the temperature to max both sides, set the direction to face only. It will be cold to start but should warm fairly rapidly even in a diesel. Once the engine is up to temperature you should be getting hot air out of the face vents, centre and side. If you are consistently getting luke warm air then it may well be your thermostat is faulty but I would expect the temperature gauge to read lower than 9 o'clock if that were the case. Once you are sure you have warm air, change to screen only.
In frosty conditions my V6 takes approximately 5 minutes or longer to fully defrost the screen, however if I close down face vents, move knurled knob to left and wait 2 minutes after starting engine, then turn on AC and screen only the screen and front side windows clear in 30 seconds to a minute.

The temp gauge gets to the 9 o'clock position after 2 miles but the air does not get very warm.