Radiator Fan 1996 318ti - Help. Detailed info provided.
 

First, thank you for reading this.

Second, I have read all of the posts in the forums in regards to the radiator fan. Each and every one over the past few days while actively troubleshooting this. I am posting my own thread due to a lack of understanding and knowledge most likely, and also for some specific information.

My radiator fan does not seem to be functioning normally, nor has it ever since I've owned the car. My first issues with my 318ti were overheating issues, leading to a blown headgasket when I first got the car. I bought it from a shader used car dealer, and suspect that he sold me a lemon in the first place. The headgasket issue has since been repaired, along with the thermostat and water pump replaced. This is why I want to make sure the fan is working before summer.

1. The radiator fan turns on with the AC.
2. I tested the Radiator temp sensor. Jumping ground to t1 turns on Low Speed Fan, Ground to t2 turns on High Speed fan.
3. I replaced the High Speed Relay and Low Speed Relay.
4. Fan still only comes on with the AC.
5. Fuse 16,41 are listed as aux fan. Fuse 16 looks good to me, im no expert. Fuse 41 is empty.
6. I read something about a fuse 48 under the dash and took it apart and see no giant orange fuses. I need to put it back together right now before the sun goes away.

Does this basically guarantee that it is the resistor on the fan?
If so do we know if there is a part number for this resistor? I searched through the net and found nothing.

I sincerely appreciate any help you give and all the help you've given over the years.

I am confused. If you jumper at the temp sensor and the fan runs on both the high speed and the low speed there is nothing wrong with the fan, the relays, or the resistor. Why do you think there is something wrong with the fan? Maybe it is the sensor albeit i don't think these ate a common failure point.

The resistor is not a commonly swapped part and is built into the fan. Some google searching will lead to a few generic part numbers. I actually bought a couple of them but never tried one before I did the swap.

Thank you for your reply Wake!

I think something is wrong because even on the hottest days I have never seen or heard the fan come on. Even today, I came home from work ( a 20 minute drive ~62 degrees out ), installed the two new relays that came in the mail, and then let the car idle for another 30 minutes. No fan.

Should I be waiting until the hottest summer days to test and see if the fans come on?

I suppose the next step is to get a thermometer of sorts and test the temperature of engine bay? Or how would I test that?

I didn't know how to test by jumping at the sensor plug - I looked it up and finally found a picture tutorial after I installed the new relays. Perhaps I should install the old relays and perform the same test? Maybe it was fixed and it didn't get hot enough?

Perhaps I should change the sensor just in case. I have 145k miles and I do not believe its ever been replaced.

The reason I'm so concerned is because I've had such terrible aforementioned overheating issues when I first bought the car - and was not 318ti knowledgeable to any degree.

Since you are in MD, I would be surprised if your fan would kick on at all this time of year. Mine doesn't run very often and I am in FL, it only runs on hot days in stop and go traffic. You said it comes on high when the AC works so that is good. Having a bad low speed resistor is a common problem, but that isn't your problem as you said te fan will run on high and low.

You may be over thinking this. When you let your car idle to get it hot did the car temp gauge ever go past 12 o'clock?

If you are super concerned you can get a new temp sensor for the radiator with a lower temp range from Pelican and others.

Watch the gauge, drive the car and have some fun with it!

I appreciate it wake. I think I'll order a sensor and install it to make me feel better, but otherwise I'll just monitor everything and go.

The temperature gauge went past 12 o'clock only once since I got the head gasket, the plastic flanges, the thermostat and water pump replaced. It was a hot summer night near the beach after a long drive and idling for a while. Ever since then, I've been worried.

It has not happened since, but thankfully I don't drive the car a lot, but it is my only car at the moment.

And I'd like to spend as much time off as I can get at the beach this summer!

Anyway, thank you again for your time.