Vent Fan Speed

[bfi2906]

I know this has been discussed before, and while there are many opinions, I can't see that there was ever a conclusive result.

I completely understand that when the vent/ac is on "Auto", the fan speed will vary to achieve the temp asap.

What i get, is the fan speed varying with the engine speed, when it's not on "Auto". 2000 rpm seems to be where the fan speed builds. But then it will slow again, with the engine speed - say at lights.

I've spoken with two dealers, and got "it's normal" and "you better bring it in for us to look at"

Anyone had a conclusive result or even better, a fixed by BMW, on this?

[MickyD]

mine goes all over the place. the display doesn't change (the number of little blocks lit up) but it seems to randomly blow harder and softer. I know our AC at home does similar to try and stir the air up more, it may be similar?

[BBK]

Only thing mine does which I assumed was normal, that it is always consistent with the setting, but on occasion it randonmly stops for about a second then comes back on.

[Nick135i]

Mine does it too. Speeds up or slows down. Every now and then it cuts out for 2 seconds.

My observation is (when set on Manual) that when the outside temp is very different from the A/C set temp the air conditioning seams to work well. i.e. no complaints on a 35deg day with the temp set at 16deg - the system seams to work well.

When the temps get closer together (outside 20deg - AC set to 20) the system seams to go into some sort of auto mode - even though it is set to manual !

I find it very difficult to find a comfortable A/C setting when I get into the car hot (after exercise etc..) on a cool day (18-20) - the car either will blast too cold air out at 16deg. However any other setting (i.e. 16.5) causes random fan behaviuor.

I tried to explaing this to the dealer - they said they have never heard of it. However at first service - they indicated that the gas level / preassure was down to 66% and they topped it up. This seams to have helped things a little - however it has only been 2 months since the service and the weather has been hot.

[beemer]

search: spastic fan

[bfi2906]

Seems it's relatively common - maybe it is "normal".

The other thing (which I forgot to mention) - if i set the drivers temp to 16, the fan would blow the koalas out of their trees. If i put it on 16.5 (or any other temp), it's just "normal". The same doesn't happen with the passenger side - that will operate quite normally at 16.

Strange set up if it is normal.

[beemer]

i forgot to mention my spastic fan when i got my car serviced this week. dam. but i will and let you know.

alot of bmw's seem to have the problem, all the loaners i have gotten have had it too.

[beemer]

okay rang sylvania bmw and told them the fan speed is totally random, i got the usual questions about what settings i put it on and stuff, so i mentioned i'd researched it, its a common problem, its the final stage resistor, and bang my cars booked in to be fixed with a loaner car supplied in 2 weeks.

so it is known about in oz.

[Zuzu]

Originally Posted by beemer

okay rang sylvania bmw and told them the fan speed is totally random, i got the usual questions about what settings i put it on and stuff, so i mentioned i'd researched it, its a common problem, its the final stage resistor, and bang my cars booked in to be fixed with a loaner car supplied in 2 weeks.

so it is known about in oz.

Thats good info beemer..

Some of these service departments must really get surprised when forum members like us tell them we have done our homework and the problem is ABC..

I am always in the service managers (Gary) ear at Sylvania with my explanation of what I "know" is the problem..

[bfi2906]

Originally Posted by beemer

okay rang sylvania bmw and told them the fan speed is totally random, i got the usual questions about what settings i put it on and stuff, so i mentioned i'd researched it, its a common problem, its the final stage resistor, and bang my cars booked in to be fixed with a loaner car supplied in 2 weeks.

so it is known about in oz.

beemer - good job. Please keep us posted on the fix. Mine's due for it's 1st service in about 1000K's, so this is very timely.

I'd love to be able to go into the dealer and let them "spin" their ususal lines, and then tell them what the specific problem is that they need to fix.

[beemer]

i got to say Sylvania bmw have really good service, so it may not be that easy everywhere.

[135x5]

My 135's booked in for an oil change next week with a bmw specialist (not a BMW dealer) and I'm going to ask about my crazy fan. But, having driven several 1 series hatches & coupes as courtesy cars over the years, I've noticed they all seem to do it, esp in 'auto' mode.

[Taymaishu]

Subaru's "Auto" setting has always been in correlation to engine speed.

Perhaps BMW is the same, but i haven't noticed. Auto = full pace at 16 degrees

[GtiGyver]

Noticed it varies less if you force recirculation ON or OFF as opposed to Auto Recirc.

[petersracing]

I think I noticed some correlation to light shining/reflected on the sun sensor on the back of the rear view mirror. Saab use the sun sensor on the dash to alter the aircon to suit the "perceived temperature" in the cabin rather than the measured temp. Does the "Efficient Dynamics" vary the fan speed depending on the output of the compressor? It'll be interesting to see results of Beemers service. If it works it seems like they better order a whole box of final stage resistors.

[beemer]

Result: fan speed resistor replaced no charge, it is a fault. They said its common in other series but not the 1, well that could soon change. i think it is common in the 1 series as all the loaners i have had have done it.

All except the 123d hatch they loaned me for the day and i gotta say off topic its a pretty impressive diesel motor, lots of speed from about 60 to 150. but sluggish off the start however. not even on the same page as the 135i. but still fun to drive. i thought it would be great for my wife but they want 60k+ for them. way too much.


oh yeah, just reading some peoples posts, your fan is spastic if it stops and starts and changes speed when NOT on auto. if your fan stops and starts and changes speed when you have manually set it on say 3 bars then its faulty.

[sparoz]

+100 ^

Spastic fan is a common fault in other series especially the E46, and I had it in the 120d as well - if you are getting it, make sure you get the dealer to fix it, especially before your warranty runs out. (Although it is actually a cheap fix - the part is like $80).

Brisbane looked for the problem for about 5 times - and finally said they have to change the face plate. As it was out of warranty, I decided to google it - bingo, it was on a Tech Bulletin. Took it to Coastline and they spot it even before I took it in.