[777ER]

I've been playing around with my A/C settings to see how I can get more airflow in cooling since it seems lacking in comparsion with my other car (2010 honda accord)

What I've notice is if I set these settings:

• Front vents ON
• AUTO mode OFF
• Auto recirculate/manual recirculate both OFF
• A/C ON
• Fan speed set to HIGH

It blows the same speed and chill as if 'MAX' mode is set...but with these settings above...after 15 to 17 mins of running, all of a sudden the air blows cold, fast, and hard like I like it.

I am able to duplicate it all the time, every 15-17 mins when I notice it, I look at the clock and notice it's been 15 to 17 mins after I left the office parking lot to the time it happens. Regardless of outdoor temp.

If I turn the car off say stop at a bank or errands and start it back up for the next trip, it won't do it until 15 to 17 mins of running.


I've looked everywhere in the owners manual for the reason it does this, couldn't find it. Also not able to manually force it to occur anytime regardless of settings.



I'm thinking the car stays in recirculation mode no matter what until it gets cool enough and then the vent from the outside opens and a rush of air starts coming out as it's running with no restrictions.

Basically the A/C is blowing cold air everytime the temp is set to cold temp, and the A/C is on but this whole thing is about the fan or blower speed issue.


Does anyone know why it does this and how can I force it to come on when I start the car instead of driving or waiting 15 to 17 mins?

[Surly73]

Originally Posted by 777ER

I'm thinking the car stays in recirculation mode no matter what until it gets cool enough and then the vent from the outside opens and a rush of air starts coming out as it's running with no restrictions.

Correct - recirc is set automatically in various conditions and doesn't indicate on the panel.

I'd like to offer some other comments, though.

Running recirc is less restricted than outside air, not more (unless something is wrong with some of the flaps in your individual car, of course). Running recirc will result in better AC performance because it does not need to extract humidity like it does from an outdoor air charge. You'll also get far less evaporator funk growing when you use recirc.

I don't know why you find that running outside air is suddenly cooler, higher volume and more refreshing. I always find the opposite. The hotter and muggier it is the more pronounced.

Running high fan speeds also doesn't remove as much humidity. If you aren't fighting a high sun load you'll get more comfortable air (and much better fuel economy) at a lower fan speed so that all moisture can be extracted and the output air is as chilled and dry as possible.

The above comments are not BMW specific.

[For what it's worth, I agree that the E90 has weak airflow (undersized fans I suspect) and programming that makes this even more apparent). E39 and F10 5-series cars I've owned or used are far better and have much larger blowers. I did an all air flaps re-init using INPA a couple of weeks ago and it seems a little better.]

[777ER]

Correct - recirc is set automatically in various conditions and doesn't indicate on the panel.

Interesting...

Running recirc is less restricted than outside air, not more (unless something is wrong with some of the flaps in your individual car, of course). Running recirc will result in better AC performance because it does not need to extract humidity like it does from an outdoor air charge. You'll also get far less evaporator funk growing when you use recirc.

Well the E90 has an characoal filter so I did more looking into it, when the blower speed is lacking and in recirc mode automatically (before 15-17 mins) I took the cover and the air filter out, see the flap is closed.

20 mins later when I pulled back into the driveway after running a couple of errands, I leave the engine running and the AC on abd blowing as pictured above when it's blowing hard and cold, I took the filter cover and the filter out again, the flap is open.

I agree running recirc will result in colder air in the cabin but in the E90's case, it's lacking airflow speed compared to the vent flap open and not in recirc mode.

As for the evaporator funk, doesn't the cabin air filter stop that from filtering the outside air?

I don't know why you find that running outside air is suddenly cooler, higher volume and more refreshing. I always find the opposite. The hotter and muggier it is the more pronounced.

The air flows faster and harder this way, when I switch to recirc mode, it's lacking airflow...there is airflow but not strong, it's kinda weak.

[For what it's worth, I agree that the E90 has weak airflow (undersized fans I suspect) and programming that makes this even more apparent). E39 and F10 5-series cars I've owned or used are far better and have much larger blowers. I did an all air flaps re-init using INPA a couple of weeks ago and it seems a little better.]

How about a project by swapping or installing a high flow fan on the blower motor?

[Surly73]

Originally Posted by 777ER

Well the E90 has an characoal filter so I did more looking into it, when the blower speed is lacking and in recirc mode automatically (before 15-17 mins) I took the cover and the air filter out, see the flap is closed.

20 mins later when I pulled back into the driveway after running a couple of errands, I leave the engine running and the AC on abd blowing as pictured above when it's blowing hard and cold, I took the filter cover and the filter out again, the flap is open.

I agree running recirc will result in colder air in the cabin but in the E90's case, it's lacking airflow speed compared to the vent flap open and not in recirc mode.

I don't disagree at all with your claims, it just shouldn't be that way. I wonder if your recirc flap is jammed. If you have INPA, run a full flap recalibration/init and see if that changes anything. On every car I've ever had (bimmers too) recirc can move more air than the flow-through setting.

As for the evaporator funk, doesn't the cabin air filter stop that from filtering the outside air?

More moisture promotes funk, and I bet the air filter doesn't stop the smallest spores from entering (it's not like it's HEPA rated or anything). If you're only cooling a recirc air charge, eventually there won't be a lot of moisture produced at the evaporator (only your breathing and sweating, as opposed to the pea soupy outside air).

The air flows faster and harder this way, when I switch to recirc mode, it's lacking airflow...there is airflow but not strong, it's kinda weak.

How about a project by swapping or installing a high flow fan on the blower motor?

Like I mentioned - maybe you should go over your car to see if there's a malfunction. You've seen that the outside inlet flaps are closing when recirc mode is set, it's possible that the footwell recirc inlet flaps aren't opening properly or fully.... It's worth a look - no need to be working around something that's actually repairable.

I'd love a bigger blower. (<-- I should really edit that)

[GoRomeo]

Check your battery...It's worth a look. Do a load test at any of your local auto parts store. Having a weak battery, features like AC and others tend to stop working they way it should.

[chronologic]

Originally Posted by GoRomeo

Check your battery...It's worth a look. Do a load test at any of your local auto parts store. Having a weak battery, features like AC and others tend to stop working they way it should.

I agree with this comment. Power management will limit accessory usage once it detects the battery starts to weaken. This happened to me. In my case, i cannot get the maximum blower speed and the rear defroster doesn't work anymore. All went back to normal operation when I replaced the battery.

[777ER]

Originally Posted by Surly73

I don't disagree at all with your claims, it just shouldn't be that way. I wonder if your recirc flap is jammed. If you have INPA, run a full flap recalibration/init and see if that changes anything. On every car I've ever had (bimmers too) recirc can move more air than the flow-through setting.

What is INPA and how do I get it or get access to it?

Couldn't hurt to try, I have no error codes and the battery is stock as it came with the car when it was new. No issues with battery.

[Surly73]

Originally Posted by chronologic

I agree with this comment. Power management will limit accessory usage once it detects the battery starts to weaken. This happened to me. In my case, i cannot get the maximum blower speed and the rear defroster doesn't work anymore. All went back to normal operation when I replaced the battery.

I hear you, but he has a problem with airflow in recirc mode only, with the engine running. IBS is not going to limit fan performance in recirc mode only if it's a battery condition problem.

Worth checking, but unlikely IMO.

[Surly73]

Originally Posted by 777ER

What is INPA and how do I get it or get access to it?

Couldn't hurt to try, I have no error codes and the battery is stock as it came with the car when it was new. No issues with battery.

You'll have to visit the coding forum to look into INPA. You could always get together with a helper and do a headstand first and look for any obstruction at the recirc inlet vents, or see if both sides (left and right) are opening fully.

As you say - it doesn't hurt, and you shouldn't have to constantly work around a problem that's actually a malfunction.

[pedrobmw]

I have the same issue with my 2007 328xi. Have taken my car twice in the past 3 years to two different dealers, and both times, they have said the AC unit is performing within spec. However, I used to lease a 2008 3-series, and the AC didn't behave that way.

I haven't timed the delay like you have, but subjectively, I have noticed a similar lag before the AC unit really starts putting out effective, high-flow, cold air.

Have you had any other luck in tracking down the problem/solution?

[Surly73]

Originally Posted by pedrobmw

I have the same issue with my 2007 328xi. Have taken my car twice in the past 3 years to two different dealers, and both times, they have said the AC unit is performing within spec. However, I used to lease a 2008 3-series, and the AC didn't behave that way.

I haven't timed the delay like you have, but subjectively, I have noticed a similar lag before the AC unit really starts putting out effective, high-flow, cold air.

Have you had any other luck in tracking down the problem/solution?

I read your other post and I don't think the problems are the same. You don't seem to be getting any cooling until your engine compartment is hot. The OP's problem seems to be improper/restricted airflow in recirc mode. (from everything I can tell).

(And I offered to look up a screen in INPA for the OP and I keep forgetting or running out of time when I'm at home. Augh)