87 Audi 5000 Radiator Fan operation suspect

My radiator fan is not working in all three speeds anymore. Somtimes it does not come on at all.
Looking at my internet parts store, I see a an Engine Temp. Sensor advertised as follows:
"There is 2 Pin. 90c Deg. Engine Temp. Sensor Used to correct radiator fan run-on. Mounted on a special bracket attached to valve cover."
Any input to this problem would be appreciated!
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What you are looking at is used on the turbos to operated the fan speed one for after run cooling. Not your problem.
The fan is three speed: - speed one operates when the AC is on and after the engine is turned off to cool the injectors on turbo engines - speeds 2 and 3 are activated by either the thermo switch on the back bottom of the radiator or by the MFTS temp switch on the head near the upper radiator hose.
It is unlikely that all these are bad so you should look elsewhere.
elsewhere: - you could have bad relays but it is again unlikely that all three are bad. Relays for fan speeds 1 and 2 are in the relay box in front of the windshield on the drivers side (US spec). Fan speed two is a very big double-wide relay in the aux relay panel under the dash by the driver's left knee. - The fan speed resistor pack could be bad but not likely as the failure mode is typically to short open and the fan will run in the fastest speed continually. This pack is located on the frame under the radiator.
>>>>>> This is very likely to be your problem: All three fan speeds are controlled by resistors to provide different power to the fan. To complete the circuit, there is a large ground wire from the fan to ground. On later models there is a fusible link in line mounted on the drivers side fender well just under the brake master cylinder. If this is bad the fan will not run at all.
Your '87 may not have this fusible link so the wiring may have burned out. you will be lucky if this has not fried a lot of the associated wiring.
The reason this happens is the fan bearings get old and dry causing high current load and heating of the wiring.
So check the wiring and fusible link if you have one.
Next. The fan motor is not shown as serviceable but it actually is if you are careful. There are good write-ups on this in the T44 forum on Audiworld. Search the history and you shall find. http://forums.audiworld.com/v8 /
Using one from a bone yard will probably not get you in a much better situation that the one you have but you could try it to save time.
TonyJ former four T44s for 12 years. BTDT ... current: 98.5 A4 TQM
martino wrote:

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wrote:

Tony-
Thanks for the time and valuable input! Appreciated!
I also have an 85 4000s Audi with a similar problem.
To fix that, I simply fabricated and installed a manual switch, which can be operated from the dashboard. Done!
As for the 87 Audi 5000 I'll try to fix it using your input as a starter.
Thanks again- martino
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