Most of the time the fan runs on Low. On High it's really loud and draws a lot of current from the electrical system. Having 2 speeds allows better enginer thermo management. Here in Southern Cal, my cars usually don't kicked into high speed until the summer or sitting in traffic.

I think the point ClubmanS is trying to make is how this negatively affects the A/C compressor.

 

My radiator fan was working on high speed all the time. Since we have had our share of very hot days down here, prior to Sunday's failure, I used to hear the fan running very loudly with the A/C on and the car in moderate to heavy traffic. In some instances, after shutting off the engine, the fan would continue to run for 5 minutes in "Emergency" mode, because the engine was running extremely hot (But the water temp gauge never warned me of any high temperatures under the bonnet).

Most people don't pay attention to the low/high speed behavior of the radiator fan and by the time the problem is detected is already too late. If your MINI has 50K miles or more, have the radiator fan be checked ASAP. If you are told that you need to replace it, don't hesitate. Just get it replaced or else it will fry your A/C compressor effectively increasing your repair bill.

Unfortunately, the relay and circuit board on the radiator fan assembly can not be replaced or repaired. You have to replace the whole thing to the tune of $300 just for the part.

 

With ScanGauge2, I just confirmed my fan's low speed mode is dead. Fan didn't turn on until coolant temp reached 233*, which is the spec behavior according to Bentley 170-3. The low speed mode comes on when temp reach 221* or when AC is on.

In the same section of Bentley. "The fan is controlled by ECM through two relays, a low speed relay and a high speed relay. The low speed relay is mounted in the engine compartment fuse box and is energized any time the fan is operating. The high speed relay is mounted on the fan housing in the relay pack. The relay pack contains the High speed relay and a voltage reducing resistor."

I'm going to check my low speed relay. And hopefully this will solve my dead AC problem.

 

Okay, so there are two relays in the engine bay fuse box that might be the culprit. The low speed fan relay and the AC compressor relay. Anyone know how to test the relay to see if its functional?

 

I got that... and I appreciate his sharing his experience.

Because it resulted in such a costly repair, I was trying to better understand how to recognize the first onset of the problem - I'm not sure I would notice a slightly "louder" fan noise as a problem.

BTW, the OEM fan assembly is shown on minicarparts.net ~$280 (I assume that is the part?). I know some will insist on OEM, but there is an aftermarket version on rockauto.com for $80.

 

Crude method...

The A/C compressor relay controls the compressor. Try remove it and turn on the A/C... it shouldn't engage. As for the fan's Low speed, it should come on when you turn on the A/C.

The High speed requires higher coolant temp. You can race (high revs) around the block a few times, stop and hold the idle at 3000+ RPM. Without air moving through the radiator, the Hi speed will eventually kick in.

 

I have replaced ac compressor and new rad. fan recharged the system . have 30 on low side 150 high side ac still blowing hot air out of vents in the car.the car is a 2003 but has the 2002 system it was made in Nov. 2002 .