Air conditioning

[Philip Fisher]

Originally Posted by Deman77

I always thought volvo ventilation system was one of the weakest points. It’s been 4 years and I can’t get used to it. In winter it will blow cold air in your face so you don’t fall asleep and in summer the insulation of the piping is so inadequate that you are not getting that cool an air on very hot days for good 15 min until you cooled down all the hot plastic pipework. Yes it’s very cold right at the point of vent exit but my i3 is a lot more effective and I believe xc90 with 4 zone has two a/c units.
Just put a dial blue and red for me and I will adjust to what works - don’t force me into your “feels like” nonsense. Plus you have to keep adjusting it on the screen.
Another point of “brilliance” is to put all the fans at the front. So when the back zones call for higher flow you have a fan at the front in ridiculous overdrive which also leaks some flow into front vents as they are not perfectly segregated from the back. 60k car and they cannot put a fan onto each vent like Citroen does for a third of the price.
Just on this feature set alone my next car will not be volvo.

Wow. That seems like quite a specific set of requirements for a small part of the car.

I am perfectly relaxed about it. I just leave on auto. Nudge up or down between 20 and 23 now and again and turn the air con off a lot of the time to save fuel and save it needlessly drying my eyes out. I also open the window when I am hot now and again too.....

On occasions like today I pre cooled the car 15mins before I left work and felt super smug getting into a pre cooled car. Now that is proper luxury!

My next car will almost certainly be a Volvo. Maybe an all electric XC40 if they ever offer 300 miles range and a sticker price of sub 40k....

[cheshired5]

Originally Posted by Quacker

The main issue is that it is dangerous to the occupants who might be in the car for hours, only to exit to a 30C temperature which may instantly result in thermal shock to their body and almost instant loss of consciousness.

The idea of climate control is to regulate the temperature to whatever is chosen which for most is room temperature.
As mentioned by Clan earlier, 20 ish °C is plenty comfortable for all year round (+/- a couple of degrees) then you don't get a massive schism between the car temperature and ambient so it would be a lot simpler if folk just read the manual and understood how to use climate control.
Even my 17 year old car has a sun intensity sensor linked to the climate module to allow cooling compensation in direct sunlight.

The chances of thermal shock from a car AC system are slim to none. Seriously, when have you ever heard of someone dying after exiting a car where the ac was too cold?
I used to work in warehouse freezers at - 25°C for hours a day and months on end and thousands of people still do.
In that scenario, when you leave the freezers for breaks, you're looking at a temperature swing of up to 50°C yet you never hear of cold workers dying of thermal shock.
Sure, you wear protective clothing but it's still f*****g freezing.

Originally Posted by Quacker

I believe that most car HVAC systems now limit the lowest temperature selectable for the cabin to around 17C. Which doesn't mean that the air exiting the vents is limited to 17C. That could be much colder if the cab temperature is well above 17C.

The temperature exiting the vents can be down to around 6°C which is when the ac compressor switches off to avoid freezing.
Dependant on outside temperature and the cabin temperature selected, ac will then kick back in around 12°C and cycle repeatedly.

This is assuming you have it on auto as the system was intended.

[Chief inspector]

Works great for me, just be aware that in ‘ECO’ it is quite, well, - economical with the cooling and you may need to nudge the fans up a bit.

[Lexman8]

I find the aircon very good with the air exiting the vents really quite cold. I always try to pre-ventilate the car on hot days like these.

On my Merc I could force the climate system into diagnostic mode and get readouts of multiple parameters. The air leaving the evaporator was typically 5C and the XC90's air temperature at the dash vents feels similar to the Merc.

[Quacker]

Originally Posted by MaDProFF

I actually think it is ok, it certainly is cool air that comes out of the vents for sure, and pretty quick after car start up.

I Assume it is an electric AC on a T8

What do you mean by "electric AC"? No matter whether it has only an IC engine, a hybrid or a fully electric car, the aircon will be more or less the same with a compressor, condenser and evaporater manipulating gas pressure differential. The only necessary difference is what drives the compressor.

[Quacker]

Originally Posted by cheshired5

The chances of thermal shock from a car AC system are slim to none. Seriously, when have you ever heard of someone dying after exiting a car where the ac was too cold?

I can assure you that up until the mid 1990's that this was a very real issue. There was a particularly famous case of a lady in America that had travelled for hours with the air-con dialled right down cold who exited the car to open a gate and passed out so quickly that she pivoted on her hips so that her head hit the floor and she broke her back.
Just because you had not heard of this issue, does not mean that it isn't/wasn't a big issue in warmer climates.

In reverse, it is the reason that very hot people that have a swim in a river are at risk from cardiac arrest and drowning, which continues to happen every Summer even in the UK. River water is always extremely cold.

[gaby]

Originally Posted by Bloke69

If I'm correct, the temp setting for the climate control is set to "feels like" rather than the absolute temperature

According to the owners manual, that is correct (XC90 MY2018 p.201):
Perceived temperature
The climate control system regulates the climate
in the passenger compartment based on the
perceived temperature, not on actual temperature.

The temperature you select in the passenger compartment
corresponds to the physically perceived temperature as
affected by factors suchas the ambient temperature, air speed,
humidity, solar radiation, etc. in and around the car at the time.

[gaby]

Some info in the owners manual "fell off":

The system includes a sun sensor which detects
on which side the sun is shining into the passen-
ger compartment. This means that the tempera-
ture can differ between the right and left-hand
side's air vents despite the controls being set for
the same temperature on both sides.

[Haldex]

Originally Posted by Philip Fisher

I just leave on auto. Nudge up or down between 20 and 23 now and again and turn the air con off a lot of the time to save fuel and save it needlessly drying my eyes out. I also open the window when I am hot now and again too.....

Same here. As a matter of fact, my Individual mode is set to run the AC in eco.

Originally Posted by gaby

The system includes a sun sensor which detects
on which side the sun is shining into the passen-
ger compartment. This means that the tempera-
ture can differ between the right and left-hand
side's air vents despite the controls being set for
the same temperature on both sides.

Cool! Didn't know this one.

[cheshired5]

Originally Posted by Quacker

I can assure you that up until the mid 1990's that this was a very real issue.

I've been dealing with cars and ac since before the mid 90s and I can assure you that what you claim is a non issue in the car industry.

As I've already mentioned, every car ac system shuts off around 6°C to prevent the evaporator freezing and you can even view the cycle (and all the other contributing data) as it is happening using Vida.

That is still the case now so even if you were able to select under 10°C as a cabin temperature, the compressor would either shutdown or the system would become frozen and start to heat up due to restricted flow.
Physics wasn't different before the mid 90s and I suspect that the unfortunate lady in your example had underlying health issues.