[Knuckle89]

I've noticed when using the climate on following settings:
-Ac turned off
-Recirculation button deactivated
-16c left 16c right (coldest setting)
-Auto deactivated
-Centre vent set to cold / midway

The temperature is steady but then every so often it'll go really cold for a few minutes. As everything is on manual modes and AC turned off I'm at a loss as to why. The ambient temperature is around 15 to 20c.

In addition the temperature stays quite cool unless I put it up quite high without AC, but weirdly with AC on it gets warmer at a lower temperature... If that makes sense.

Perhaps nothing and just a quirk but it was noticeable to my passengers also.

Any advice appreciated. UK model 320d

[LMK5]

Originally Posted by Knuckle89

I've noticed when using the climate on following settings:
-Ac turned off
-Recirculation button deactivated
-16c left 16c right (coldest setting)
-Auto deactivated
-Centre vent set to cold / midway

The temperature is steady but then every so often it'll go really cold for a few minutes. As everything is on manual modes and AC turned off I'm at a loss as to why. The ambient temperature is around 15 to 20c.

In addition the temperature stays quite cool unless I put it up quite high without AC, but weirdly with AC on it gets warmer at a lower temperature... If that makes sense.

Perhaps nothing and just a quirk but it was noticeable to my passengers also.

Any advice appreciated. UK model 320d

Keep in mind that there is really no fully manual mode. The system will always try to drive the cabin temperature towards the setting you choose, in this case 16C. Perhaps that can explain at least some of the behavior (behaviour in UK?).

[Liwanji]

Originally Posted by LMK5

Keep in mind that there is really no fully manual mode. The system will always try to drive the cabin temperature towards the setting you choose, in this case 16C. Perhaps that can explain at least some of the behavior (behaviour in UK?).

That confirms my suspicion. I always have the feeling that the climate control system can override the manual setting and turn AC on/off as it sees fit...

[grancoupef36]

the system has a humidity sensor to prevent windows from fogging (ateast thats the idea) and whenever it feels its too humid... on comes the a/c. theres also no way to turn it off, sounds good on paper but in practice its just a nuisance

[eluded]

It's German, you're never truly in manual mode

[Knuckle89]

Hmm that's good to know thanks. I did look on the on board manual, and I thought the humidity sensor was only active when auto was turned on. It's not the end of the world but I didn't have this happen on my previous bmws.

In fact it also steamed up a bit yesterday when we all had fresh coffee, so guess it's pretty rubbish also!

[Skiddz]

Originally Posted by grancoupef36

the system has a humidity sensor to prevent windows from fogging (ateast thats the idea) and whenever it feels its too humid... on comes the a/c. theres also no way to turn it off, sounds good on paper but in practice its just a nuisance

Exactly. I live in south Florida (it's a bit humid here ), and I've learned I can be proactive and be "ahead" of the humidity sensor by opening my windows and sunroof prior to starting the car. This works most of time, but I have to always be on the lookout for reduced airflow when driving (stopping at a traffic light for example) or the humidity sensor can come into play.

I love my car, but would gladly pay to throw the both the humidity and rain sensors in the trash so each respective system is controlled by me.

[HighlandPete]

Originally Posted by Knuckle89

Hmm that's good to know thanks. I did look on the on board manual, and I thought the humidity sensor was only active when auto was turned on. It's not the end of the world but I didn't have this happen on my previous bmws.

In fact it also steamed up a bit yesterday when we all had fresh coffee, so guess it's pretty rubbish also!

Wet clothes, steam from coffee... what is the issue with using the A/C to dehumidify the cabin?

The whole purpose of climate control is to sort out humidity and temperature. When we disable part of the function (like switching off the A/C function), of course it can't be as effective in unobtrusively working in the background.

Latest BMW HVAC systems do have overrides to keep the cabin is some sort of demisted state. Misting is also viewed as a safety issue, in HVAC design documents.

Re the A/C function intervention, in BMW's own language:

The IHKA can reliably prevent fogging of the window glass through selective control intervention.

BTW, why run at 16C? I'd suggest that is why you feel the cold when the A/C cuts in to defog, it is now trying to chill the car (lowest setting). If it was say 18C or even 20C, you wouldn't likely feel it in anything like the same way. In fact if you ran with A/C on, at say 19 - 20C, you wouldn't feel any change, it would easily be keeping a constant temperature at 15 - 20C ambient, with virtually no air flows. Do it much more efficiently than the climate control trying to work "with its hands tied" as it were.