Hello from Niagara Falls Canada

[Rushfan69]

Just purchased an '08 X3 3.0si with 220,000 km
It's Platinbronze with black leather(ette?) interior.
I also own an E46 330xi and my experience with it lead me to the X3. I thoroughly enjoy driving the E46
I'm also a licensed mechanic and have owned and worked on a full gammit of automobiles.
I am an avid Subaru Outback lover for winters here, but my current 2001 VDC is at 320,000km and showing more rust underneath than I am comfortable with.
The X3 was stuck in limp mode when I looked at it. Couldn't rev it beyond 2000 rpms. Wouldn't drive more than 5km/h. I pulled a few codes off it. One being a cylinder 4 misfire. The owner looked perplexed to see so many codes present/historical.
Also, the valvetronic servo was unplugged, but I can see how that's possibly knocked off when installing the engine cover. I plugged it back in. The throttle response improved right away, but the misfire was still there.
I explained to the owner that there are a number of resons why the vehicle could be stuck in limp mode and I think it scared him into salvaging something a bit more than a salvage yard price for the vehicle. Needless to say, I paid very little for the vehicle
I towed it home after I purchased it. Swapping the plug and coil from cyl 4 to cyl 3 took the misfire with it, so a used coil and a new plug quickly rectified limp mode and the engine runs smooth now.
Now to find out why the cooling fan does not come on with AC
Here is the list of history codes; (not present)
Engine
2EFE DME Electric Fan Activation
Misfire at low tank fill level
2A39 DME Valvetronic adjustment range
29D0 DME misfire Cyl 4 (present)

ABS
Brake-light switch permanently actuated
5DCF DSC Conrtrol unit undervoltage
6E3E DSC Steering angle senso adjustment required

Transmission
No codes present

SRS
MRS Power supply
A3 MRS No message from DSC control unit
A1 MRS No message from DSC control unit

[X5Sport]

Hello and to the Forum.

AC cooling fan not starting is often caused by low pressure in the system and is in order to avoid pump damage. If the pressure is fine then you may have a power fault at the fan itself. If the system hasn’t been used for a while then the seals start to leak. A regas and leak check will confirm. These systems need special AC lubricant added as well as gas, but any expert should know that (I hope!).

The fan has a DC supply but uses PWM control for speed (same as the E46 does). Unless you know your way around them it’s pretty much unfixable except if a broken wire, and a new fan may be your only option. You’ll ideally need a scope to see the PWM waveform.

[Rushfan69]

The cooling system builds up a good pressure in the upper hose. Level looked good when I opened it cold. It will sit on the mid range of the gauge, but I'm guessing that is BMW's "piece of mind" 30 degree variance zone on these, similar to the E46.
I've heard the fan won't come on until it reaches 115? That's pretty hot in my books. My E46 runs a steady 85 - 87 degrees at any speed over 60km/h (40mph) and tops up around 92 if it's a hot day, idling in drive with AC on.

The AC compressor comes on and blows cold for a few minutes until the condensor gets heat-soaked.

Would replacing the controller on top of the rad be a good start? I have a spare from my E46 aux fan. Can't imagine they are much different.
I'm not sure how the fan switch in the rad hose is configured, but most are a 2-wire, temperature triggered switch. Jumping the terminals should engage the fan on high speed? Correct me if I'm wrong.
I suppose I can send 12 volts directly to the fan to test operation if all else fails.

Update:
Took the fan assembly off the rad. (It wasn't even hanging on its hooks). Removed the fan blade and the snap ring that holds the rotating magnet on the center shaft.
There was a lot of greenish-blue corrosion at the point where the field wires are clamped to the copper buses.
I cleaned off the corrossion with a mixture of baking soda paste and a toothbrush, sprayed electrical parts cleaner on the whole thing, then proceeded to flow some solder at every joint where the field wires are clamped. I see now that along side the heavy power and ground wires, there is a light green signal wire as well. This wire must be the PWM signal to the internal fan module, so applying B+ and B- to the heavy wires will do nothing here.
I reconnected the fan, started the engine and turned on the AC with gauges hooked up. The low side dropped to around 35, then started climbing, as did the high side. The compressor shut off when the high side hit its limit. Still no cooling fan operation.
I guess I'll be scouring the salvage yard for a compatible fan module.
Mine is a Temic ECL-G4
I wonder if the E90 fan module is the same. There are a couple E90s in my local yard.

Update:
Got a matching Temic 600W fan from an 2010 X3 in a local U-pick yard.
Plugged it into the system and started the engine and then the AC. The fan came on right away and ramped up to speed. Runs smooth with no abnormal noise.
Cost was CAD $17.70 +tx ($20)

[X5Sport]

If you have a look at Reaoem (on line BMW Parts database) and put the last 7 of your VIN into ‘Serial number’, it should bring up your model. Check the part numbers to what other cars the module(s) get used on. Depending upon spec you may have a higher or lower power fan unit. It’s determined by vehicle spec, model and sales market/region.

As an example on my X6, the standard fan is 650W but I have a tow bar (hitch) so it’s fitted with an 800W fan.