Very Noisey Fan

[geo123]

alright guys go easy as its my first post
ok i have a 320 year 2000 saloon 89000 miles
theres a couple of faults but after som reading i think i have a rough idea of what im looking for with these first two
when i turn on the rear demister the radio goes all funney crackly ect
im going to have a check for some loose wires ect
also the fan comes on sometimes and sometimes not the display shows the fan on full but nothing
im going to check the final stage thing on the a/c
but this one has me stumped
when i start the car after a coupleof min the fan comes on as it should
only a minute or two later its running id say twice as fast as it should the noise is unreal
the temp gauge sits in the middle where it always has done
but the fan doesnt switch off for as long as the car is running the fan is on
until i turn off the engineand the top pipe on the radiaton is very hot
but the lower one is cold also the radiator is cool but the engine feels very warm
when from cold if i remove the radiator cap i see water pouring in at the top when i start the engine so im guessing the pump is good
only other thing i can see is like a small sensor on top of the fan like a small matchbox could this be faulty if so would the fan run at full all the time
what is this small sensor called
thanks for taking the time for reading this
and thanks in advance for all if any replys
great board keep it up

[jkloese]

I had a 2000 323i and the rear when I turned on the rear defrost it did the same thing to my radio. Someone had told me that BMW had a fix for it, but I never went and had it checked since it was out of warranty, and I pretty much never use the rear defrost in Florida.

As far as the fan problem, Im not sure what the "noise" your hearing is but the fan will change speeds depending on the engine temp. I had problems with the fan in that car also, I was just getting ready to change that fan out when the subframe tore loose from the chassis, so I never had a chance. Good luck with it though.