Hvac question

[Helloball]

Why would the hvac air sampler fan inside the control unit continue to run with everything switched off on the control panel(fan switch, heat temp selection wheels) all off? Keeps running even when key is off. Only to stop it is to pullfuse 20 under hood. Sometimes it stays running and sometimes it doesn’t when I turn key off. Btw my car has the analog simpler hvac controller. Not the auto sword style.

[Helloball]

Ok so maybe I’m crazy! I read around a little bit and found out that other models the fan times out for whatever reason. So I went and sat in mine for awhile and sure enough the fan shut off two consecutive times after 20 minutes on the nose. For what reason would the cabin air sensor fan need to stay running for 20 minutes after the car is shut off?

[shogun]

independent ventilation? Some models have this, copied from the E36 manual: BMW's Independent Ventilation (also known as Park Ventilation). Page 87 of the 96+ 318,323,328 Manual: Independent ventilation*
This ventilates the vehicle's interior and lowers its temperature using the heater or the air conditioner fan. The system is operated by the onboard computer, refer to page 77. You can set the time for the system to
start; it will remain active for 30 minutes. You can also turn it on and off directly. As the system uses a substantial amount of electric current, you should refrain from activating it twice in succession without allowing the battery to be recharged in normal operation between use. The independent ventilation is available for use when the outside temperature is above 60 5F (166), but not when driving. The air comes out through the vents for the upper body area. The vents must therefore be open for the system to operate.

E34 also has it as optional extra http://www.bmwe34.net/E34main/Upgrade/Ventilation.htm

[Helloball]

I think you’re misunderstanding what is running. It’s not the main hvac fan under dash/firewall. It the tiny cabin air temperature sampler fan thats mounted to the hvac control module above the ashtray. Not the main blower fan

[shogun]

fuse 20 is for
EWS II drive away protection
instrument cluster, check control
multi function clock
park, tail, underhood lights
park ventilation/with IHKR / F3
IHKR/F3
OBC IV

Maybe your IHKR control module is defective? That 64118367951 has 2 plugs, pull one after the other and test when the fan stops, then check the ETM which pin that is https://www.programainc.com/item_det...x?idproduct=65
study the ETM how the fan could be powered even when ignition is off and key is removed.
Maybe another member had the same problem and can help?

[Helloball]

Thanks Shogun.

[moroza]

A defective IHKR module can cause this. The most expedient solution is a replacement module.