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I jumped the wires on connector and fan comes on, replaced the temp sensor in radiator, made no difference. Also, it does not come on with A/C turned on. At what temp is this to kick on? gauge stays right in the middle of gauge. Just purchased this car and received paperwork that shows stat being replaced at dealer recently. Took readings on hoses, stat housing, radiator with temp gun, and nowhere is over 205 degrees. Thought I saw somewhere these has a 215 deg. stat, but even so it should still kick in with A/C on I would think. Any help out there, before I wire it to a switch.
Thanks, Gene
 

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BMW CCA 1405
1997 BMW Z3 1.9
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5,168 Posts
My 4-cylinder has one fan which is electric. The thermostat maintains 206F until stopped in hot traffic. Around 212F the temp drops suddenly back to the low 200s, so I think that is when the fan comes on.
You cannot tell the temperature from the needle gauge. It stays in the middle as long as the engine is not cold or overheating, like from 165F to 225F.
You evidently have a 6-cylinder with mechanical and electrical fans.
I think the electric fan is supposed to come on when both the compressor and the blower are turned on.

If the temperature gun reads the cooling system parts at around 205F, and the AC works, you don't seem to have a problem.
 

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Thanks for your reply. Mine is 2.8, has a clutched fan and motor as well as electric in front of condenser. My thinking was even though it did not get hot enough to trigger it, it still should come on when a/c is operating I believe. You're right about the gauge, you really don't know where temp is other than in normal range. Just would like to know when it is supposed to kick in. It's starting get into some hot weather and don't want it overheating. Just have to keep a jumper wire with me.
 

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Your 2.8 aux fan has two speeds. Low speed comes on when the temp sensor on the side of the radiator reaches 91C. High speed comes on when the temperature reaches 99C or if the AC is turned on. Shorting the Brown to green should turn on low speed fan. Brown to gray or A/C compressor should turn on high-speed fan. The only difference is that a big resistor is inserted into the low-speed circuit. All of this is controlled by two relays in the underhood relay panel.
Both the fan motor and resistor are common failure items.
A few cars have this set-up miswired: http://www.bimmerfest.com/forums/showthread.php?t=385482
 

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Discussion Starter #5
Thank for the info Blacklane, since I know the motor works when powered direct, I'll proceed to check relays tomorrow.
 
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