winter air con

[marinabrid]

On the old Mk1 manual air con   i could turn it on any time even in winter freeze and it would click on and with heat it would clear all condensation in few mins
with this mk2 with auto climate   i have getting misted up on side and rear and it dont seem to clear it at all,
is the air con supposed to come on    i know its 5c or something  but its odd the old one seemed far superior with its manual button
or am i missing some setting thats supposed to engage the compressor in winter ,  is it   windscreen setting  or  auto maybe ?  any clues    thanks

[gregers]

i agree the aircon in the old mk1's was a hell of a lot better then the mk2's.
we test drove a mk1 with aircon and the missus WAS very pleased to see me,
mk2 really was disappointing.
my smax isnt that great to be honest either.

i thought the compressor only engaged to condense the air in the summer??

[Mirez]

No the compressor must engage for the AC to function. It's restriction on the Mk2 is below 5*c and is designed to stop 'icing' of the evaporator. Personally, I think that's VW being overcautious and not having a simple sensor to measure this but then I presume the reason to implement it was that they saw the problem 'in the field'

[marinabrid]

went out earlier and when i got in car to return it was steamed up,  the outside temp was 7c
so when i put the heater on  cleared the screen but still condensed on the rear windows when home   is the aircon working to clear the mist  ?   or do you have to put the settings to auto or windscreen or some other setting   or is it just a poor crap system in this case  automatic cc  not as variable as the old Mk1

bit confusing  ??

[johnnyroper]

They put frost protection on climate to prevent compressor damage.
We get it at work on the trains the system is an automatic type so has protection built in after incidents where saloon temp demanded cooling but ambient temp was low the compressor would still run but would cause the evap to freeze,if the low pressure sensor failed to operate then liquid refrigerant would travel back down to compressor causing it to hydraulic shearing the drives.
That said under slung compressor modules carrying 20kg of fridge will be a damn sight colder than that fitted to a car,so it probably is a bit of over kill on car manufacturers behalf.

[Chrispb]

iirc think it's +5deg the aircon is disabled even when still in the AUTO mode as you say to avoid damage to compressor.

[marinabrid]

thanks Chris
So odd that the mk1 would work at 5c   they must not have had a disable switch on it then  i presume ? 

[johnnyroper]

Manual air con does not normally have the ambient temp cut off as there is no input from sensor for it.
It usually relies on low temp inside car causing evap to freeze then shuts it off on low pressure. Having said that if you have air con with heating on the air inside car will be high enough to prevent freezing.