Jeff Bergman

Does anyone know what activates the cooling fan? Or, how long does it take for the radiator cooling fan to turn on.

Any info would be greatly appreciated.

I was told I needed a new radiator fan. Replaced it with a new factory fan and shroud. seems like the new fan doesn't work, or the dealer found the wrong problem?? I also replaced the thermostat and lower radiator hose sensor. After replacing everything, I ran the engine for about 5 minutes - no fan. I also turned on the AC - still no fan.

Does the computer need to be programmed that there's a new fan??

Any suggestions?

Thanks.

txag_530i

What is the year and model of the car?

twh

See if this is at all useful:
https://www.google.com/url?sa=t&rct=...06923889,d.cGc

Jeff Bergman

twh. Thanks for the link. That didn't really help. It didn't really cover how to activate the fan. At least, not that I could tell.

txag 530i, my car is a 2008 550i. From what I can tell the water pump is not electric. I'm looking for a way to test to see if the fan works. I have the old one and a the new one. Do you know if there's a way to bench test the fan? In other words, can I apply 12V to it? There's 3 wires. Two large gauge and one small gauge.

twh

Jeff, Have a look here. This is the wiring diagram. This is what you can get from that web site bmwplanet.

Jeff Bergman

twh. Thanks. That's a pretty detailed diagram. Sadly, it's over my head. Are you sure this is for the 550i? I'm getting the impression that the 550i may have a different system than the 528 and 535?? Not sure. There's a lot of chatter about an electric water pump. Mine doesn't seem to be electric.

Do you know how to interpret that diagram? Can you tell what the (3) wires on my electric fan are? Can I bench test the fan??

twh

This is for the N62 engine as of March 2007 builds. You can see that if you look up the tree on the left hand side of the screenshot. Yes, you do not have an electric water pump. It's understandable that people assume you do since there aren't many 550's out there as compared to 6 cylinders.

But, and please don't take offense - if the diagram is over your head, you may not want to mess around with bench testing this thing. Something you should be able to do is check the two fuses (10A and 100A) shown in the upper left of the diagram. I don't know where the cut-out relay is located, but that is also something that can go bad.

txag_530i

BMW E60 5-Series Cooling Fan Replacement (2003-2010) - Pelican Parts Technical Article

For a quick test of the fan, turn on your A/C. The fan should come on. If it does not, it may be faulty. You can also try unplugging your coolant temperature sensor. The fan should run on HIGH. Keep in mind with this technique, a fault code will be set and have to be cleared. Or you will be stuck with a check engine light for a few days until it automatically clears.

Cooling fan test - Bimmerfest - BMW Forums

Under certain operating conditions, the engine control activates the electric fan at various speeds.
The electric fan is activated by means of a power output stage directly on the fan motor. The motor control unit activates this power output stage by means of a square-wave signal with duty factors (variable pulse width) between 10 and 90 % thus controlling the various speeds of the electric fan. Pulse duty factors less than 5 % and greater than 95 % do not trigger activation but rather they are used for fault detection purposes. The power output stage features its own positive and ground supply.
The fan speed is influenced by the coolant temperature at the radiator outlet and the pressure in the air conditioning system. The fan speed is reduced as the vehicle speed increases.

Jeff Bergman

Thanks guys for your feedback. Apparently this is a little more complicated than I thought. So the fan is not a simple DC motor. From what I can see, the only way to manually test the motor is to use a signal generator and connect it to the leads of the motor. Not sure if I want to take that on not knowing how to set the signal generator.

One thing I've always noticed about this car is that when I turn on the AC, it sometimes takes several minutes before the compressor even turns on to generate cold air. So it seems that testing this stupid thing may be best left to the pros???

As far as the fuses go, do you know where the 10A & 100A fuses are located? I only found a 40A fuse in the trunk area that has a fan symbol. Does anyone have any clear diagrams labeled with the fuse block layout and which fuse(s) are the fan fuses??

And, where the fan relay is and the best way to test that relay?

I had no idea this was going to be this complicated. The dealer diagnosed this as a bad fan motor.

I managed to replace the fan myself. Messy job and a little tricky, but not too bad. A bit of time.

Do you guys know if the computer needs to be programmed to recognize the new fan?

Thanks for all your thoughts.

Jeff Bergman

twh. No offense taken. I'm pretty handy and better than average with cars, but all the computer control is a bit much for me, especially when I see all the code letters with no clear designations of what they mean or where they go or are.

One thing, you mentioned that I clearly don't have an electric water pump by looking at the left side of the diagram. I looked at that. I don't see any reference to a water pump at all. What are you looking at?