When is the power steering fan suppoesed to kick on? Ive been having a pump issue with it shutting off when overheating, and have yet to catch the fan on....Whens it supposed to kick on?

Thanks

 

It's yoked to the engine cooling fan. When the ECM turns on the engine cooling fan, the power steering fan turns on too. There's an over-temperature sensor that shuts down the power steering pump if it gets too hot, but there is no communication between the pump and the fan.

The engine fan turns on when the AC is on and pressure is at 8 bar, and goes to high speed when the pressure is 18 bar. It also turns on to low speed if the coolant temp is 221 deg F and turns off at 214. If it goes up to 234 deg F the fan goes to high speed, and goes back to low speed if the temperature drops by 7 deg F.

So says my manual. YMMV.

 

Awesome, greatly appreciate it. I just took the P.S fan off to bench test it, It feels like the bearing is going out in it. Im thinking this may be my P.S overheating problem.

 

When you say the "A/C is on" is that when the compressor cycles, or when the swicth is on?. Reason I ask is I "think" I have lost the first stage fan. When I put the cluster into diagnostic mode, the fan came on at 105C and then off at 100c or so. According to what you state, that is the low stage fan. When I put the A/C switch on, there is not fan that turns on, but when the A/C compressor cycles on, the P/S fan and the cooling fan come on. When the compressor finishes it's cycle (20-30 seconds), the P/S fan tunrs off and I have no cooling fan running at all.

I didn't have the nerve to let the engine get higher than 105C to see if there was a 2nd stage fan.

I have read 2 or 3 dozen threads on this, but none of them clarify what "A/C on" is. There is one video that says the 1st stage fan comes on when you turn the switch on and it will cycle to 2nd stage when compressor is active but it also states that the P/S fan is connected to the first stage. Mine doesn't seem to function like that.
If the P/S fan stays on with the first stage, does it run constantly while the A/C is on? Or does the P/S fan cycle off with the first stage fan, when the 2nd stage fan kicks in?
--anybody have a normal working can that can be know good tested for comparison? mine is an 05 Cooper with manual a/c controls, and only other option is the H/K..
I've seen ML's video but he has an 06 S with the auto climate control, do the systems work the same?

My first guess is that I have a 1st stage fan relay dead, and when the ECU selects the 2nd stage fan when cycling the compressor, it also signals to start the P/S fan (as a backup measure) but under normal operation is redundant since the P/S fan is already on with the first stage.

My next guess is the refrigerant pressure is low and not reaching 8bar to cycle the 1st stage on. Although the A/C reaches a center vent temp of 40F parked on an 85F day so that would lead me to believe the A/C pressure is good.

Is there a video or sound clip that demonstartes the difference in sound between the 1st stage and 2nd stage fan? It would be easier to diagnose a "problem" if I knew what the first stage sounded like since I've only ever heard one fan speed (in the year I've had it.

For the life of me, I still can't believe that MINI would allow an engine to reach temperatures over 200f before turning on a fan. I would think it would be closer to 185 if they were so concerned with overheating electrical components underhood (ie P/S pump and fluid). Maybe the abnormally high cycle temp is what is leading to the actual failure of the internal fan resistor... Just a guess...

Hopefully the community can digest my questions...I've worked on Honda's for almost 20 years and this car has got me stumped. The service manual doesn't even explain exactly how the system works.

Jeff

 

Well, took the connector off and powered up the 1st stage and 2nd stage fans, both come on. So I know my fan in good, check voltage at the connector for the 1st stage wire when compressor cycles and have power during cycle, but no power when A/C switch is on, but does cycle when coolant temp reaches 105C..

Still stumped as to why the fan will not run when the A/C switch is on. Fan stage 2 does not cycle with the P/S Fan, only the 1st stage..

 

SOLVED IT!...

Called a BMW tech I'm fairly friendly with and he said, even though spec is usually spec, there is a tolerance on pressures by as much as 0.5 bar, especially on A/C systems. SO...I evacuated and recharged the A/C system until the high side pressure read 8.5 bar (125psi) (instead of spec of 8.0 bar/ 116 psi) at it's low side of cycle and 155/160psi on the high side of cycle and low and behold...A/C fan came on and stayed on!!.. never once did 2nd stage fan come on, but was too cold outside to get engine temp above 90c (194F)..Evacuated and measured charge and was 1.2 lbs (instead of .91+/- 0.2 lbs) of freon. System continued to cycle now but will report pressures come springtime to make sure slight overcharge does not effect anything else and pressures are not way out of whack..

FYI for those troubleshooting this weird problem and "think" you may have a 1st stage fan out, check your A/C charge..