[2Newts]

I have encountered an odd problem.

On long trips in high temps and high humidity (last Sunday it was 93 and humid), the air stops blowing into the cabin. I can hear the fans, but even if I turn the fan up to the maximum setting on manual, no air comes into the cabin.

I toyed around with a lot of changes.
- It happens whether on auto or manual settings
- It happens in Comfort, Sport, and EcoPro
- It happens regardless of where the air is supposed to come out (feet, panel, windshield)
- It happens no matter the setting of the recirc button.
- It happens whether the temp is set to something reasonable or unreasonable (I tried everything between 65 and 75 degrees)

But if I turn off the a/c via the button on the right side, so that the green light turns off, then the air returns to the cabin. It blows at any and every level as long as the a/c is turned off. Then if I turn the a/c back on, the air continues to flow into the cabin, gets cold and holds for a few minutes. After about five minutes the quantity of air begins to decrease and by ten minutes it's back to no air coming in.

I can then repeat the process with exactly the same result.

Has anyone experienced the same? Does anyone have any thoughts?

Cheers, and thanks.

2N

[Billfitz]

Your coils are freezing up. With the compressor off the ice melts off the coils, so it works again until it freezes again. Both the heat and humidity contribute to the problem. Have your dealer check out the AC system.

[bavarianride]

There were online posts saying the F30 evaporator(or condenser?) can ice up with prolonged AC usage on hot days.

[401FlaGATOR]

There are a lot of posts on this, commented on one as recent as this weekend. Your evap coil is freezing up, whatever anyone says this is not proper there is yet to my knowledge no consensus from BMW as to the cause, is it a defect in the design, manufacture, improper charge, leak, or some other as yet unkown factor?

[Billfitz]

Originally Posted by 401FlaGATOR

is it a defect in the design, manufacture, improper charge, leak, or some other as yet unkown factor?

The usual cause is a system that lacks sufficient capacity. If the compressor has to run continuously, never cycling off so the coils get a chance to 'rest', with sufficient humidity they'll freeze up. Insufficient refrigerant can be a factor, because that can cause the compressor to work too hard. But still as the old saying goes it's not the heat, it's the humidity. In very humid conditions setting the temperature no more than 15 degrees below the outside temperature can make all the difference. At 120 degrees in the desert you'll never have a freeze up, as there's nothing to freeze.

[Blubaron79]

This is a known issue with the evaporate sensor. Take to the dealer and they will fix.

[Wires]

I had the same issue, and it was because I had it in "auto" but didn't set the "intensity" to anything more than the far left (my e90 didn't have this bizarre feature).

If you run the A/C, you need enough airflow to the condenser to pull the cold off or it will ice over. It appears in this car when that happens, all the vents get closed to cycle air through the condenser to thaw it back out.

Just keep your intensity higher (or far right) or the fan higher in manual mode, and it should be fine.

[401FlaGATOR]

Originally Posted by Billfitz

The usual cause is a system that lacks sufficient capacity. If the compressor has to run continuously, never cycling off so the coils get a chance to 'rest', with sufficient humidity they'll freeze up. Insufficient refrigerant can be a factor, because that can cause the compressor to work too hard. But still as the old saying goes it's not the heat, it's the humidity. In very humid conditions setting the temperature no more than 15 degrees below the outside temperature can make all the difference. At 120 degrees in the desert you'll never have a freeze up, as there's nothing to freeze.

If the system is properly designed with proper charge and heat loading on the evap coil it should be able to run continuously without ever freezing up. I am assuming BMW has provided sufficient capacity for all possible conditions (95F ambient outside, 75F internally, etc). There are reports of many F30 freezing up so there is either a manufacturing error, design error, some kind of leak that is manifesting across many cars, or an improper level of charge from factory, thermostat sensor defect or something else. One guy had the service dept. tell him he had a low charge, which will cause high superheating at the evap and the temperature of the coil will dip below freezing point causing condensate to freeze. Normal temp of an evaporator coil that is working properly is above the freezing point of water (about 40F).

[gregorilla]

I also have this problem. It has happened exactly 2 times both when temp was between 90 and 100. I think in both instances I was using the blower at full speed in "Max AC" mode. I agree with the consensus of frozen coils however I would think that by using the Recirculation ON this should not happen because there is only so much interior moisture. I have not tested this but I'm a bit confused because in the Max AC mode recirc should have been set on.

Well hopefully I won't have to have any more of these sweaty drives as I'm trying my luck with a new model later this year. But I will call the service advisor and see if they recommend anything.

[RoundelM3]

I just had this occur - 1st time in 3 1/2 years of ownership - and had it fixed at the dealership. I could hear the fan running very fast, but very little air coming through the vents. They installed an adapter that moves the temperature sensor to make it function more accurately. I thought it might have been a problem with the refrigerant pressure, but the tech told me there is a bulletin about it. This occurred during very high humidity and temperatures here in SE North Carolina recently, but so far it has not recurred.

[andradexoscar]

Hey,

I have recently encountered the same problem. Did you ever find a solution for this?

Thank you

[kwstandard]

Originally Posted by andradexoscar

Hey,

I have recently encountered the same problem. Did you ever find a solution for this?

Thank you

Look here:

https://f30.bimmerpost.com/forums/sh....php?t=1741499

[Desertnate]

And this thread which is very recent too.

https://f30.bimmerpost.com/forums/sh....php?t=1738193