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Discussion Starter #1
I just purchased a 2001 325i over a month ago and have some ac/electric fan issues. I looked over the forums for a while but could not find something with my exact problems so I am starting a new thread on this topic.

Here is what I know
1-During the hottest day of the summer (near 100F) the car temperature gauge started climbing past the midway point while I was in stop and go traffic.

2-The ac air coming out of the vents was not cool during those really hot days

3-No matter whether it is cold/hot, changing the temperature on the climate control does not seem to significantly effect the temperature of the air coming out at the vents. Setting the climate control to 67F or 59F seems exactly the same.

4-The air coming out of the vents blows erratically like it is pulsating between high and low speeds.

5-The electric fan in front of the car has never spun as far as I have checked and I checked many times.

6-The check engine light comes on when I do a lot of stop and go driving, error code P0369 (cam shaft position sensor). It will turn off if I do a lot of highway driving.

From reading the threads, the fact that the car started to overheat (1) and no cold ac (2) seems related to the electric fan not spinning (5). From driving the car, it seems that this is also related to the check engine light (6). My guess is that if the fan is not coming on, then the cam shaft position sensor gets too hot but I am not sure.

Also from reading the threads, the fact that the air coming out of the vents blows erratically (4), seems to be due to the final stage unit/resistor but does this also cause the climate controls to not work properly (3)?

So my question is could the FSU cause the electric fan to not spin at all and therefore all the rest of the problems? Or is there more than one problem? For example do I have to replace the FSU, and the electric fan? Finally what about the temperature sensor in the lower radiator hose? Is that a possible problem too?

Things I have tried. The fan blades spin if I mechanically push them. I checked that the blower/compressor fuses are okay. I directly connected the fan (at the relay) to a DC source (although I later found out that I think this shouldn't do anything as the fan takes in a variable pulse signal).

Sorry if this sounds complicated but I am just trying to be as detailed as I can be for easier diagnosis.

Right now I am trying to stay away from the dealer so any help would be much appreciated.
 

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Discussion Starter #4
Wow, amazing that there are some replies here. Thanks already.

A quick added note. I tried checking power to the prongs on the relay to the ac fan. They seemed to work okay. SolidJake does this then mean the ac fan has to be replaced? I guess that is what the second link also basically explained. I was hoping to avoid that since the fan is a lot more expensive than the FSU. Or is there some other sensor you meant I could check?

I understand that camshaft position sensor is important but I have never had any engine issues. The reason I thought it might be related to the fan was the light is not consistently on. The check engine light typically only comes on in stop and go traffic and almost never on the highway (I thought when there is enough airflow).
 

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I'm not sure as I have no encountered this problem per say. I was also take the fuse out for the fan (the BIG 50amp fuse I think on the left side) and clean off the contacts with some sandpaper. That worked for someone here recently.


If it's only in stop and go it might be the cooling system is letting the car run too hot triggering the sensor, but it can also mean the sensor is on its way out.

I had an intake camshaft sensor before, cleared it and a month later it came back by stalling the car on me multiple times.
 

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Discussion Starter #7
GoingNuts, when I wrote AC fan, I did not mean the fan pushing air out of the vents, but the electric fan in front of the car. So it seems like the electric fan is the issue alright but the only thing is would a broken electric fan also cause the air coming out of the vents to pulse like it is switching between high and low speeds? The pulsing of the air coming out of the vents is what people normally describe as a faulty FSU system but did you get this pulsing when your electric fan broke?
 

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I was getting the problem of no air con when stationary. Read through loads of similar threads. I think I went through this all last summer and it's been on my list of to-do jobs. I live in the UK so it's only about 2 weeks of the year that I actually need the air con. Pretty much never switch it on the rest of the year...

So I thought I would take a look. I pulled apart the plugs for the aux fan and the lower coolant temp sensor. I was getting the 12v at the aux fan connector supply side. I got various ohms readings between the positive, negative and signal pins on both sides of the connection. I got 2050 ohms on the temp sensor when cold, well it was 26.5 degrees outside, so coldish. Then I took at look at the fan, just through the grill, and stuck a screwdriver on it to see how freely it span and it took quite a push to get it to turn at all the first as though it was a bit stuck, but then it started spinning freely.

Started the car, without the air con on, and didn't get the start up test. Then I switched the air con on and air started coming out coldish as it usually would. I thought I'd let it run up and see what happened. Then a couple of minutes in the aux fan kicked in!! first time I think I've ever seen it run! Checked it for a while and kept it running and I had nice cold air the whole time!

I don't know if it was because of one of the connectors or not, but it was probably due to the fan being a bit stuck.

Just thought I'd share that as it might be worth people with the same problem to give that a try, especially if you hardly use the air con.

I'll copy this post to the other threads I have open on the same issue.
 
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