Hi all,
Just a guide I obtained from BMW-Sg forum. Hope this helps. Original Link is here: http://www.bmw-sg.com/forums/bmw-3-series-owners-general-discussion/70769-bad-smell-coming-out-air-con.html
Mouldy Odour from A/C, on all series with air conditioner (IHKR) or automatic air conditioner (IHKA)
Objective:
A mouldy smell can be detected inside the vehicle for a short time in either heating or air conditioning mode. This happens in particular immediately after the engine is started with the air conditioner or automatic air conditioner switched on, on after switching the air conditioner off during a journey.
Cause:
The cause of this objection does not lie in a fault of the air conditioning system or automatic air conditioner, nor in the vehicle. The odour is caused by environmental influences during the period of operation of the air conditioning system.
The continuous condensation of air humidity on the evaporator when the air conditioner or automatic air conditioner is operated over lengthy period creates an ideal habit for bacteria and other microorganisms.
Together with impurities brought in from the outside air, these can cause support microbes to grow on the evaporator, resulting in a mouldy smell.
As higher the temperature with sufficient humidity in the heat exchange, as faster the microorganisms can be grow.
Replacing the evaporator does not produce a lasting result, as microbes are still able to form again.
Recommendations regarding the avoidance of the mouldy odour:
- Regular cleaning of the evaporator as described in our Technical Service Bulletin.
- By regular change of the micro filter, the entry of impurities can be minimized and occurrences of the above-mentioned issues can be delayed.
- After the journey it is recommend switching the air conditioning system off briefly before the destination (5-10mins) (add. Switch the heater system on) so that the condensation in the heater box can dry by the air circulation.
- “To burn” micro organisms out: Place car into the sun, start engine, switch on circulating air, adjust heating and blower to maximum achievement, close all doors and windows and wait 10 to 30 mins. The car heats itself thereby very strongly and hot air from the interior kills all microorganisms in the heat exchanger by the operation with circulating air.
The objection can sooner or later occur again, however depending upon climate and country situation.
Warranty reimbursement is not possible, as the problem does not constitute a technical defect.
Bayerische Motoren Werke AG
