Poor warm up and de-misting

[RUM4MO]

The dehum is only happening because the moisture in the cabin air is getting passed over a cold zone and so some of the moisture drops out of the air and condenses on the evaporator - which will only get made cold if the chiller is passing refrigerant through it - and at temperatures below, maybe +4C, this will lead directly to the evaporator surface icing up.

[Adam_013]

Only other thought was if the different type of the Aircon gas being used affects the dehumidifing aspect of it, which I can't imagine.

Sent from my Pixel 2 XL using Tapatalk

[vc-10]

The Golf 5 had an 'Econ' button, instead of an A/C button. Pressing 'Econ' deactivated the A/C compressor, which otherwise worked by itself to decide if it should be on or not.

[RUM4MO]

Only other thought was if the different type of the Aircon gas being used affects the dehumidifing aspect of it, which I can't imagine.

Sent from my Pixel 2 XL using Tapatalk

No,this replacement for R134a is trying to be very thing that R134a was in terms of performance, so that it can be used as a "drop in" replacement as tends to be the way things go, but it will possibly be less efficient, far more environmental friendly at point of use - but maybe gets past the seals a bit more, which suits the fridge service industry but will cost us all a bit more I'd guess.

[Andy Beats]

Here's a thing now.
Currently 0C at our office, thick ice on the cars.
Started mine up to warm it up, the aircon light has come on.
If the aircon doesn't acutally work below 4C, why bother making the light come on.....?

[RUM4MO]

Just means my guess at "+4C" as the limit was wrong, its a long time since I last saw the official "switch off" lower limit mentioned - and I don't tend to use the AC in winter, so I've never ever witnessed the lower limit in force.

For you, maybe tomorrow morning?

Edit:- it could well be that as most cars will have built in protection in the form of a temperature probe on the evaporator, as well as an ambient air temperature probe, that the user will never notice when the chiller system is protecting itself.

[Andy Beats]

-3C this morning, aircon light still came on when directing air towards the screen.

[david.stark]

I made a lengthy topic on this issue. I bought 2 of those dehumidifier pads and a nice windscreen cover for when it gets frosty. Both have helped.

[Andy Beats]

I have a 'pingi' pad which I put on the dash every night.
I notice it's turning away from blue towards pink already, which shows it's soaking stuff up and will need microwaving soon.
I can't be bothered with one of those windscreen covers, I'd much rather just leave it idling for a while.

[RUM4MO]

-3C this morning, aircon light still came on when directing air towards the screen.

I'm now guessing that the control of that chiller compressor, ie its displacement will be limited when temperature drops below a certain level and you will not know about it, and so the light will always come on as normal.

One thing to understand, if you do not know this is, most if not all new models of cars have moved away from the old electro-magnetic pulley clutch system, and so they are now fitted with a constantly driven compressor which allows a very small ammount of refrigerant to be pushed round the system when you are not requesting cooling, this keeps all the system seals wet as well as all the rubber piping, so minimises leaks that used to be caused if you did not use the AC system regularly. These new versions of AC compressor are known as variable displacement compressors and they only pump enough for the system requirements at all times, so as they will have a temperature probe fitted to the evaporator, they can stop it running too cold in cold ambient conditions.

[Andy Beats]

-3C this morning, aircon light still came on when directing air towards the screen.

I'm now guessing that the control of that chiller compressor, ie its displacement will be limited when temperature drops below a certain level and you will not know about it, and so the light will always come on as normal.

So you think the aircon is on restricted performance or even off altogether, even though the light is on?
That would certainly explain the poor demisting.
Disappointing when I've not seen the same drop in aircon dehumidifying performance from any other make.

[Adam_013]

Yeah, especially coming from a previous polo and never having this issue with Aircon.

Then again I never had the fan speed issue either - which I'm assuming is smart charging stuffs.

-3C this morning, aircon light still came on when directing air towards the screen.

I'm now guessing that the control of that chiller compressor, ie its displacement will be limited when temperature drops below a certain level and you will not know about it, and so the light will always come on as normal.

So you think the aircon is on restricted performance or even off altogether, even though the light is on?
That would certainly explain the poor demisting.
Disappointing when I've not seen the same drop in aircon dehumidifying performance from any other make.

Sent from my Pixel 2 XL using Tapatalk

[Muldoon]

Yeah, especially coming from a previous polo and never having this issue with Aircon.

Then again I never had the fan speed issue either - which I'm assuming is smart charging stuffs.

I'm now guessing that the control of that chiller compressor, ie its displacement will be limited when temperature drops below a certain level and you will not know about it, and so the light will always come on as normal.

So you think the aircon is on restricted performance or even off altogether, even though the light is on?
That would certainly explain the poor demisting.
Disappointing when I've not seen the same drop in aircon dehumidifying performance from any other make.

Sent from my Pixel 2 XL using Tapatalk

Adam - you mentioned fan speed issues and smart charging - would this be a perceived change in fan speed / noise? I have noticed the wipers go slow and then speed up (thought it was my imagination at first) - could this be some device to save energy and vary the voltage going to different equipment?

[Leif]

Why? I hate air con. Why does it insist on coming on?

The benefits of aircon are all year round, I think you're unusual in hating it.

I think quite a few people, albeit a minority, find it dries out the air causing discomfort especially to eyes.

[RUM4MO]

So you think the aircon is on restricted performance or even off altogether, even though the light is on?
That would certainly explain the poor demisting.
Disappointing when I've not seen the same drop in aircon dehumidifying performance from any other make.

The same thing must be true with any car with AC, when you think about it, if you create a "colder than ambient air" zone in a car cabin air conditioning unit, unless you can pulse heat onto the evaporator assembly, at low ambient temperatures the water stripped out of the air will freeze on the surface of the evaporator assembly as its surface needs to be colder than the incoming air temperature and smother it with ice which will then stop the flow of the incoming air from passing through the evaporator. That is why the delivery of refrigerant needs to be limited. I have not checked the paths that incoming air can take as it passes through the airbox which contains the evaporator matrix and the coolant water, ie heater matrix, but normally it will get controlled by motorised flaps blending both the HOT and COLD "airs" to achieve good temperature regulation.