Okay, I did search and read every post that was relavant to any overheating issue and radiator fan problem. Here is what is going on. I have also posted this in another thread if it looks like deja vu to you.

Can any of the tech gurus hel?? I have a prob overheating especially when in stop and go traffic and with the air on. It's an '02 mcs 35k (owned it since 18k). Don't know if it has had the harness tsb done or not, I will check with stealership tomorrow. *update- there was no record of it being done, and they said that it is not covered and that I have to pay out of pocket. Is this true?* I have never blown a fuse and ps works fine all the time.

I know that my fans are not running. I removed the ps fan, cleaned it and bench tested it. works fine. I checked EVERY fuse; all interior fuses(drivers foot well), all engine bay fuses (even under box). I switched several of the relays to see if that changed anything. When the car is in diagnostic mode, I checked the temp, and above 101 I can feel the fan relay click on but the voltage at the fan plug does nothing.

Technical test results:The fan plug has three wires Brown (ground) and two red w/blue (hot I assume). One red is larger than the other and has constant power to it, ignition on and off. The other does not ever change (0 volts). I tested the main fan and it ran fine when I applied 7 volts to the smaller red w/blue wire and no change with voltage applied to wire typically attached to the constant power(duh). Engine temp instantly droped 10 degrees w/fan on. I also voltage tested the red w/ blue wires under the box and they all had power. Fan does nothing when a/c is activated either. I dont know what is wrong.
Please help me as it is my wifes car and it has already overheated a couple times.

 

so the cooling fan does work when you applied voltage to it?
but it doesn't run even with the a/c on?

 

yes both fans run fine when I applied voltage to the each fan plug respectively. Niether fan runs under any conditions when plugged in. No blown fuses.

 

coolant temp sensor? relay? do a search on how to get into the cpu to get actual temp dr.o or somebody posted it once . it's easy . just can't remeber lol

 

I'm leaning toward herbie's idea: temp sensor. Everything else seems to be working ok, so somewhere in the system, there is no signal being generated to tell the fan to turn on. Quote from Bentley:
"The engine coolant temperature sensor is located in the cylinder head next to the thermostat housing. The sensor is a two wire type whose signal is sent to the ECM and used as input for the radiator fan, fuel control, ignition timing, and coolant temperature gauge."
I believe the switch is a Normally Open type that doesn't pass the signal until a certain temp is reached. (Close at 221F open again at 214F). check with a multimeter. When cold, it should read high (infinite) resistance, when hot should drop to the 0 ohm range.
-s-

 

probably just 5 volts on this but get into the habit of disconnecting it from power when checking the ohms , just to avoid damage to meter .

 

There is a single temp sender that the ECU uses for fuel metering, fan control and the temp gauge/light. If the temp gauge or light is registering an overheating condition, then there is a problem starting with the ECU and going on through the fan control circuit. The ECU might be defective and not sending out the signal to turn on the relay for the slow fan speed. The relays, the wiring and even the connectors can be culprits here. If turning on the a/c does not start the fan, especially if the engine is already hot, it's a good chance the ECU is at fault. Pulling the fan realy and jumpering the terminals (87 and 30) in the fuse box should start the fan. If not, there is a problem in the wiring. With the engine hot and the a/c running the ECU will often engage the high-speed mode of the radiator fan. This is actually a separate circuit, with the relay that does the switching residing on the fan shroud near the center of the radiator. If this does not work, there could be an issue again with the ECU, the wiring, or grounding problems. There are also four hidden fuses under the fuse box, one of the 50 amp ones is involved in the fan circuit (I am not anywhere near my diagrams to tell you which one, unfortunately).

 

all fuses under the box are fine. I put the car in diagnostic mode like the DR. suggested. It reads fine and will go up and down when I manually run the fan. This tells me that the thermostat is fine. The relays click on/off when the temp changes, but I will try to manually jump the relay wires to see if the fan starts. I hope to hell its not the ecu. Where would I get one, would the dinan performance ecu solve the problem if this were the case?

 

Yay, I got it fixed. I don't know exactly what the problem was, but it finally blew the 5 amp fuse in the engine bay. I think it was a faulty connection somewhere that I had unplugged. This fuse was previously in good conditionbefore today. Replaced the fuse (which I had done before) and voila, fans turned on. Brandon at Portland MINI (503-771-MINI) was able to help me out as well. Good guy. Thanks for all the replies.

 

Jeep just a little note. If you have a early production MINI. install a updated Power steering fan motor. I have seen alot of crazy things like overheating
and different symptoms. The fan is on the bus system. When it hangs up or stops spinning it can cause overheating,blowing fuse like#5 you found even warning lamps in the cluster to light up. Plus the newer style fan motor has a built in module to control the fan better under certain conditions. Also the circuit the bus system is directly linked to the PS pump itself. I have replaced
alot of these early productions pumps and motors.

Good Luck

 

if you could hear the relays for the fan clicking,but no fan coming on ... then the contacts of the relays are most likely dirty . pull the relays and clean the contacts if possible .

 

I cleaned all the plugs etc with electrical parts cleaner when I took them apart. I asuume that is why it finally blew the fuse, because it finally made a connection. I also did it to the fuse panel (battery disconnected of course). I plan to change to the updated fan as Portland MINI told me of the differences. Thanks guys.