westsidebalto

I'm perplexed by a problem I had in my 04 545i last night. During a two hour highway drive, about an hour in I noticed the AC fan was barely putting out any air. When I cranked it to Max AC, the fan speed noticeably increased to it's normally loud max speed, but only a trickle of air came out of the vents. All vents were open and all vents in the climate menu were set to max and max cool.

Today, I started the car and immediately some white particles (dust?) came out of the center vents, but otherwise the AC worked fine.

Anybody think this is the fresh air/circulate flap failing?

Maybe it's a mouse inside and it's eating insulation and temporarily clogged the vents?

westsidebalto

I have had the "klima 9c54" error before, which is the AUC sensor as well. Perhaps that is it.

jtbgonesailing

Is it a situation where evaporater coil is icing up? Have you pulled codes with a BMW compatable reader? Could have a bad coil temp sensor or low on refrigerant, first two items to come to mind, absent any diagnostics.

westsidebalto

No, I haven't tried to pull codes yet (but can). The air coming out was cool, there just wasn't much of it and the fan was clearly spinning. I wouldn't have heard the fan if it wasn't trying to spin, but again I think it was a blockage of some type?

Razzy530

i also experienced the same issue. wonder what it could be and i dont think its a CODE issue. its a hardware issue like a partially blocked Flap or something like that. Restarting the car seems to help and only happens on longer trips where the auto recirculation does its thing opening and closing. Thats my take

westsidebalto

Thanks Razzy. It definitely felt like something was blocked. I'm going to rip it all open this weekend from both sides and see if I can find anything. I may also replace the AUC sensor for the auto recirculate since I know it's faulty.

jtbgonesailing

When the evaporater coil ices over, it will cut the air flow. Highway driving, extended drives is when it typically happens. Next time turn of a/c and turn on ventilation. In short order you will feel the volumn of air start to increase as the ice on the coil melts. Might even get some ice flakes or water droplets blowing out of center vents as it defrosts. When you think the volumn of air is back to normal, turn the a/c on again and see if it cools again with good volumn of air moving.

westsidebalto

Interesting. I'll have to remember that. It was a particularly hot and humid night on the way home, but also, I ran the AC for 3 hours prior to parking it in a very hot/humid underground garage for about 6 hours prior to the drive home (garage was worse than outside temp/humidity). Perhaps extra condensation had been introduced in the garage and it froze.

jtbgonesailing

You still need to pull codes. Suspect you are either a little low on refrigerant or the temperature probe in the evaporator coil, behind dash, isn't working properly...