2003 MCS

Has reached maximum temperature three times - once in a big snowstorm, thought it was snow packed in front of the radiator so it couldn't breathe, another about 4 months later while idling in front of a Fedex office, 40 degrees out, then once more today in front of work.

Before the overheating issues, the cooling fan would come on when it was supposed to, and usually at the end of a spirited run after I parked and stay on for a good ten minutes. Now, the fan never comes on at all. So, between that and the fact that the overheating only happens when at idle, I've determined that there's a control issue with the elec. rad. fan.

Brought it into my shop (I work at a Toyota dealer) and they looked at it, tried to jump straight power to the rad. fan, no luck, so they told me to replace it. Being the resourceful person I am, I looked on here, read about how the PS fan and rad fan are linked.

-Threw the car in the air, checked the fan, seems to spin, but unplugged it anyways.
-Found the 5A fuse blown, car wouldn't start (odd?) replaced it, car started, still no fan.
-Put car in diagnostics mode (19,7) watched temp, never climbed over 94 on way home. Sat at idle in front of house, climbed over 104, still no fan.
-Went out after dinner, pulled 5A fuse again, still looks good. Plug back in, unplug/plug two connectors on DS of radiator for fan, turn AC on, pull fuse again, plug fuse in - bam - fan. Smooth fan, high speed. Stays on for 5 seconds, then dies. Pull fuse, wait a few seconds, put back in - 5 seconds on high, then nothing. Bang on relays, nothing. Turn ac off, pull fuse, put back in, nothing. Swap relays (#2/#4) no change.

Bottom line - cooling fan works, but only if AC is on, and I pull the fuse and put it back in, and then it will come on and go off at 101. If AC is off, no fan - let it climb to 104 again.

What is it that's not working properly? What do I need to replace?

 

It's normal for a working fan to kick on when AC is on. On most cars (MINI's too) the switch to AC bypasses normal fan control and turns it on whatever the temp. Could be a bad temp sensor. Have you had the service done for the wiring harness/rewiring done for ps fan and cooling system?
-s-

 

Sometimes the resistor in the fan burns out and no longer functions correctly. You can hard wire the fan to stay on, I know Danny from MINICORSA knows how to do it, not sure how myself. Give him a call and see if he can help you out.

 

It looks as though whatever signal/power that should be getting sent to the cooling fan when the temperature reaches 95 or 101 isn't sending power when it should. It seems to work as designed with the A/C on. I'm under the impression that it would be a relay, but I've played with the ones in the box - are there separate relays attached to the fan itself? If so, can they be changed?

I may just wire a switch to the fan - is that what you mean (above)? Anyone else done this?

 

Another interesting find. Pull the third white fuse in the box (for the radiator fan) and after 5 seconds, fan comes on. Fan will stay on until temp goes below 101. Put relay back in - no fan w/o A/C.

Tried one of the other known good relays in spot #3 - no love.

WHAT is going on here?

PS - called my local MINI dealer - the wiring fix to separate the ps fan and the rad fan is NOT free - quite expensive, in fact. So, I'm SOL there too.

 

Bentley manual says the fan comes on at low speed at 105 C, high speed at 112 C. I checked mine last nite and bingo, the fan starts at 105 C. Is it possible you didn't get to 105 C in your tests?