Water in cabin filter

Stu667 · 06-19-2023, 10:51 AM

Hi all. Recently in the warm weather we've been experiencing in the UK I've had cause to run the air con at full blast a few times. It seems to be working well, except once I switch it back to 'auto' from full blast, there's been that really bad whiffy air con smell for a little while. It isn't detectable in normal operation and I run the air con permanently on auto climate control.

I last replaced the cabin filter in October '21 as part of routine maintenance so I thought maybe it's time for a new one. Ordered a Mann Frecious Plus replacement, which wasn't cheap, but I value my lung function which is already on the poor side. Anyway, as I was replacing it, I noticed a small trickle of what appeared to be water in the filter housing base, and a little bit of gunk. No detectable odour from either the old filter or liquid.

Is this normal or something I should be worried about?

Billfitz · 06-19-2023, 01:44 PM

Condensation on the AC coils is normal. It makes its way through a tube that exits in the drive shaft tunnel. It's the source of the puddle you'll see on the ground if the car's been parked for a while with the engine running and AC on. That tube could get clogged, causing the condensation to back up. It's easy to check, on a warm and humid day let the car run for a bit with the AC on and see if a puddle forms under the car.

Stu667 · 06-19-2023, 04:01 PM

Quote:

Originally Posted by Billfitz

Condensation on the AC coils is normal. It makes its way through a tube that exits in the drive shaft tunnel. It's the source of the puddle you'll see on the ground if the car's been parked for a while with the engine running and AC on. That tube could get clogged, causing the condensation to back up. It's easy to check, on a warm and humid day let the car run for a bit with the AC on and see if a puddle forms under the car.

Thanks for that.

I do frequently see a water puddle beneath the car so I'd be surprised if the tube was blocked.

The old filter itself didn't seem damp or smelly so I'm not sure where the water came from. Perhaps there was some residual water in the system somewhere that maybe leaked down with the vibration of me pulling the filter out?

Ran the new filter on full AC for a little with no bad smells afterwards, so fingers crossed.

06-19-2023, 10:51 AM	#1
Stu667 Private 6 Rep 55 Posts Drives: 2014 320D F30 Join Date: May 2011 Location: Cheshire, UK iTrader: (0)	Water in cabin filter Hi all. Recently in the warm weather we've been experiencing in the UK I've had cause to run the air con at full blast a few times. It seems to be working well, except once I switch it back to 'auto' from full blast, there's been that really bad whiffy air con smell for a little while. It isn't detectable in normal operation and I run the air con permanently on auto climate control. I last replaced the cabin filter in October '21 as part of routine maintenance so I thought maybe it's time for a new one. Ordered a Mann Frecious Plus replacement, which wasn't cheap, but I value my lung function which is already on the poor side. Anyway, as I was replacing it, I noticed a small trickle of what appeared to be water in the filter housing base, and a little bit of gunk. No detectable odour from either the old filter or liquid. Is this normal or something I should be worried about?
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06-19-2023, 01:44 PM	#2
Billfitz Lieutenant General 8243 Rep 16,082 Posts Drives: '15 328iX GT Join Date: Jan 2015 Location: New Hampshire iTrader: (0)	Condensation on the AC coils is normal. It makes its way through a tube that exits in the drive shaft tunnel. It's the source of the puddle you'll see on the ground if the car's been parked for a while with the engine running and AC on. That tube could get clogged, causing the condensation to back up. It's easy to check, on a warm and humid day let the car run for a bit with the AC on and see if a puddle forms under the car.
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