Nissan Note 2009 - Demisting and AC

Honest John Back Room » Technical matters
What is life like with your car? Let us know and win £500 in John Lewis vouchers | No thanks
View Threaded
Fri 20 Dec 2019 22:46
Nissan Note 2009 - Demisting and AC - TQ

My heater would demist all the windows without the AC on (it had no gas so I never used AC for 5 years). In 2018 I got it re-gassed and used AC during the hot summer 2018. Now for the last two winters the heater will only demist the windows when the AC is on. With the AC off the heater works fine but it fails to demist. Can someone explain why this is and how I can demist without AC ? .....Thank you.

Reply | Report as offensive | Link
Fri 20 Dec 2019 23:03
Nissan Note 2009 - Demisting and AC - Big John

Using aircon removes moisture from the air passing through the heating/cooling system via the evaporator. Moisture condenses on this and then should drain away via the evaporator drain. Couple of things to consider:-

  • If you use the aircon to demist the moisture condensed/removed by the evaporator should drain off but some will remain which will deposit on the windscreen when the car is next started which will condense if the screen is cold! Suggestion - use the air con to clear the screen but then when everything warm turn the air con off and drive for some time which should clear the moisture out of the system
  • Is this drain blocked? - it's a possibility if the aircon wasn't working for a few years although you usually get a wet carpet in the summer if this the case!

Reply | Report as offensive | Link
Fri 20 Dec 2019 23:05
Nissan Note 2009 - Demisting and AC - bathtub tom

Is your heating/ventilation on recycle or fresh air?

Have you cleared the plenum chamber (the bit under the windscreen where incoming air goes in) of leaves and other detritus. You'll need to lift up the bonnet?

When was your pollen filter last replaced?

Reply | Report as offensive | Link
Fri 20 Dec 2019 23:16
Nissan Note 2009 - Demisting and AC - TQ

Thanks for those suggestions.

I replaced pollen filter 2018. When AC has demisted windows and I turn it off but leave the heater on the windows mist again quickly. I have lifted the bonnet and cleaned the drain holes with a long wire, I do this often. The other suggestion about the AC drain being blocked is not something I knew about but never had a wet carpet. The ventilation is set to fresh air and not recycle (I did once try recycle and it made matters worse).

Its not a huge problem but I'd prefer to sort it. Do you think running the heater on full without AC for a long M.Way journey (next week) will help?

Edited by TQ on 20/12/2019 at 23:18

Reply | Report as offensive | Link
Fri 20 Dec 2019 23:34
Nissan Note 2009 - Demisting and AC - elekie&a/c doctor

All good advice here. Something else you may want to consider , is that the plastic material which forms the heater box ,gives off a vapour which coats the windscreen . So it is important that the glass is kept clean.

Reply | Report as offensive | Link
Fri 20 Dec 2019 23:47
Nissan Note 2009 - Demisting and AC - TQ

Yes, I smell that vapour from time-to-time. The screen also get covered again in vapour even after a damn good wiping! On the whole it seems like there are too many variables to solve this (minor) problem so I will wait until April and see if I can get through to Oct without using the aircon at all (like in the past) and hopefully whatever is causing the misting will have dried out! I've had the car since 2009 and this is the first problem I have had so hardly worth spending money on.

Reply | Report as offensive | Link
Sat 21 Dec 2019 14:00
Nissan Note 2009 - Demisting and AC - SJCA

Might be worth looking at the Nissan Note Owners club website. This has been discussed recently.

Reply | Report as offensive | Link
Sat 21 Dec 2019 21:05
Nissan Note 2009 - Demisting and AC - TQ

Thanks SJCA...will look

Reply | Report as offensive | Link
Sun 22 Dec 2019 09:46
Nissan Note 2009 - Demisting and AC - Andrew-T

Any slight leaks from the heater - which should cause a slow drop in coolant level but may be too small to make the front footwell damp?

Reply | Report as offensive | Link
Mon 23 Dec 2019 22:49
Nissan Note 2009 - Demisting and AC - Big John

By the fact you never had a problem when the aircon wasn't working and you do have a problem now implies an issue somehow with retained condensate moiisture. Might simply be a poor design!

Edited by Big John on 23/12/2019 at 22:49

Reply | Report as offensive | Link
Mon 23 Dec 2019 23:55
Nissan Note 2009 - Demisting and AC - TQ

Thanks for that suggestion BJ....sounds not insensible.

I'm going to tryout something suggested in the Note forum, namely leave a domestic heater inside the car for a couple of hours with the windows down 2cm thus allowing the interior (of the windows) to dry out completely. I'm kind of hoping it will solve the issue.

Reply | Report as offensive | Link
Wed 25 Dec 2019 09:50
Nissan Note 2009 - Demisting and AC - mss1tw

Every car I've ever owned with A.C does this - I assume moisture is held at bay somewhere and when the A.C. is turned off it gets blown out and condenses onto the cold windows.

You could try leaving the setting on footwell only so it hasn't got a direct route to the screen

Reply | Report as offensive | Link