3 series air con query
3 series air con query
Author
Discussion

elise2000

Original Poster:

1,991 posts

249 months

Monday 6th July 2020
quotequote all
Evening

The air con on my 3 series (2018) is fairly feeble when you switch it on for a while (maybe five mins) then all of a sudden seems to kick in and become much more powerful- is this usual? Never really noticed until now as abroad in 30ish degree heat so need it!

Cheers

Sim89

1,620 posts

237 months

Tuesday 7th July 2020
quotequote all
Hello,

Having the same thing - 2014 F31. It really struggled to cool when it was above 30 the other week, even on full strength it is quite poor in terms of fan speed and temperate.

I had it regassed a year ago, it's cold but nothing spectacular.

I've also had the situation where if you use max AC, the drivers side will blow cold and the passenger side gives up and just blows warm outside air.

Unimpressive.

No idea what the issue is or if there is any fix.

gizlaroc

17,251 posts

254 months

Tuesday 7th July 2020
quotequote all
If it is starting low or blowing warm from one side the pressure is too low.

I think it needs to be at least 31psi for it to work exactly as it should.

I would get it in somewhere for a regas and see what they say, they are really sensitive to the right pressure, ie enough refrigerant in the system.



When it is working right, with the centre vent dial set to maximum cold and the car set to auto with temp at say 18ºc it should almost give you brain freeze and be far too comfortable to have blowing in your face.

As the pressure drops the car will shut down some of the vents so it only cools the driver, some models they didn't change for RHD so driver gets warm air, and the speed drops lots too.

Edited by gizlaroc on Tuesday 7th July 09:35

elise2000

Original Poster:

1,991 posts

249 months

Tuesday 7th July 2020
quotequote all
gizlaroc said:
If it is starting low or blowing warm from one side the pressure is too low.

I think it needs to be at least 31psi for it to work exactly as it should.

I would get it in somewhere for a regas and see what they say, they are really sensitive to the right pressure, ie enough refrigerant in the system.



When it is working right, with the centre vent dial set to maximum cold and the car set to auto with temp at say 18ºc it should almost give you brain freeze and be far too comfortable to have blowing in your face.

As the pressure drops the car will shut down some of the vents so it only cools the driver, some models they didn't change for RHD so driver gets warm air, and the speed drops lots too.

Edited by gizlaroc on Tuesday 7th July 09:35
Thanks. Will take it in to bmw to check. Shouldn’t need regassing on a late 2018 car with only 30k on the clock I’d have thought, but we’ll see!

xjay1337

15,966 posts

148 months

Tuesday 7th July 2020
quotequote all
gizlaroc said:
If it is starting low or blowing warm from one side the pressure is too low.

I think it needs to be at least 31psi for it to work exactly as it should.

I would get it in somewhere for a regas and see what they say, they are really sensitive to the right pressure, ie enough refrigerant in the system.



When it is working right, with the centre vent dial set to maximum cold and the car set to auto with temp at say 18ºc it should almost give you brain freeze and be far too comfortable to have blowing in your face.

As the pressure drops the car will shut down some of the vents so it only cools the driver, some models they didn't change for RHD so driver gets warm air, and the speed drops lots too.

Edited by gizlaroc on Tuesday 7th July 09:35
Interesting.

this may be similar situation and may help OP
recently I noticed that my AC would be cold to start with then over time it would go cold (EG on a longer drive).
I also had a weird scenario where despite both dials being set for 17c then the passenger side was cold and the drivers side was coming out hot!

It went into BMW and they found nothing wrong with any of the flaps / motors behind the dash and only suggested low AC as a cause. never really knew why or how low AC would impact dual zone climate control but hey.

it got regassed and seems better now but i need a longer journey in hot weather to tell.

gizlaroc

17,251 posts

254 months

Tuesday 7th July 2020
quotequote all
xjay1337 said:
Interesting.

this may be similar situation and may help OP
recently I noticed that my AC would be cold to start with then over time it would go cold (EG on a longer drive).
I also had a weird scenario where despite both dials being set for 17c then the passenger side was cold and the drivers side was coming out hot!

It went into BMW and they found nothing wrong with any of the flaps / motors behind the dash and only suggested low AC as a cause. never really knew why or how low AC would impact dual zone climate control but hey.

it got regassed and seems better now but i need a longer journey in hot weather to tell.
It is built in safety feature to make sure it doesn't run dry, it knows when the pressure is low that there is not enough refrigerant in the system.
So it slows the whole system down and it only sends cool air, albeit at low speed, to the driver. However, on many cars this is not swapped over for RHD vehicles, so the driver stays with warm air blowing on them.


You can test this using INPA to set each vent on/off and force air speed. If all that works as expected you pretty much know it is low refrigerant.
My local BMW didn't know anything about this and said it was showing 28psi so fine, however I knew this was not fine and took it down the road to STS who immediately said "Blowing warm from one side and not very powerful even on max blower settings? You just need a top up mate."

£20 later and working like a charm.


Of course a sealed climate system shouldn't be losing anything at all, but this was on the E91 now with 161,000 miles on it and 11 years old, and it was only down slightly, but enough to put the car into fail safe mode as far as climate is concerned.



Sim89

1,620 posts

237 months

Wednesday 8th July 2020
quotequote all
This would make sense re it being low and just blowing to the driver.

I had it leak tested and re-gassed a year ago. The car is 6 years old with 50k, seems strange to be suffering from loss of pressure at that age.

xjay1337

15,966 posts

148 months

Thursday 9th July 2020
quotequote all
gizlaroc said:
It is built in safety feature to make sure it doesn't run dry, it knows when the pressure is low that there is not enough refrigerant in the system.
So it slows the whole system down and it only sends cool air, albeit at low speed, to the driver. However, on many cars this is not swapped over for RHD vehicles, so the driver stays with warm air blowing on them.


You can test this using INPA to set each vent on/off and force air speed. If all that works as expected you pretty much know it is low refrigerant.
My local BMW didn't know anything about this and said it was showing 28psi so fine, however I knew this was not fine and took it down the road to STS who immediately said "Blowing warm from one side and not very powerful even on max blower settings? You just need a top up mate."

£20 later and working like a charm.


Of course a sealed climate system shouldn't be losing anything at all, but this was on the E91 now with 161,000 miles on it and 11 years old, and it was only down slightly, but enough to put the car into fail safe mode as far as climate is concerned.
Interesting.

I think now the only issue is with that stupid dial between the two central vents (that goes blue/red)
Before if I adjusted that it would make hot air come from the top vents.
Now it makes literally no difference.
Air con works fine throughout etc.


I thought it was an electronic/resistance switch but the tech seems to think it's literally a physical lever. Either way it's not right. And I'm not sure how I can get them to believe me, plus I already paid for a bit of diagnostic (was below my warranty claim limit).

To get hot air I have to turn up the temperature now which is annoying. Before i could leave the dials at 18 and just move the dial in the vents to red.


Edited by xjay1337 on Thursday 9th July 11:53

gizlaroc

17,251 posts

254 months

Thursday 9th July 2020
quotequote all
The dial allows you to adjust the air on your face separate to the overall cabin temperature.
Why every car doesn't have this is beyond me, I really, really miss it in other makes.

It should stop you getting ice cold air in your face and getting brain freeze during boiling hot days and stop you getting hot air in your face in winter when the outside temps are freezing.

This time of year it will tend to go from ice cold to just cool, in the winter it will go from hot to fairly cool.

I tend to leave my temp set to 21ºc for the cabin and just move that dial around a bit.
It makes more difference in the winter between the hot and cold and remember, 21ºc in winter will kick out warm air, the same in summer will kick out cold air, it is trying to keep the cabin at a certain temperature, 21ºc.

craigjm

21,615 posts

230 months

Thursday 9th July 2020
quotequote all
If it’s anything like the new 2020 model you can adjust the intensity of the aircon. When I picked up my long term hire car it was crap because the system was on the lowest setting. You have to tell it the extent to which it can use the blowers

gizlaroc

17,251 posts

254 months

Thursday 9th July 2020
quotequote all
craigjm said:
If it’s anything like the new 2020 model you can adjust the intensity of the aircon. When I picked up my long term hire car it was crap because the system was on the lowest setting. You have to tell it the extent to which it can use the blowers
Yeah, auto is different on different models.

Our F11, E91 and E86 it adjusts the temp and the speed, where as our F31 it just adjusts the temp to get the cabin correct, however, you adjust 'power' separately.

Not sure which I prefer really?