Re: Audi Cooling - Update to Archive submit (Oops?)

[Dave Head <dhead@sundial.sundial.net>]

After further research, the AC high pressure switch (in front of condensor,
next to muffler) also controls the medium speed operation. Under high
pressure it closes, connecting the 2nd stage relay directly and bypassing
the 3 wire thermoswitch located in the radiator. If your system has the
problem of constant 2nd stage (medium speed) operation with ignition on, you
probably have a sticking HP switch. Changes to my previous submission are
indicated by asterisks.

At 07:27 PM 5/20/96 -0400, I wrote:
>Got my new Thermoswitch from Blau today - Stocked under part number:
>443 959 481 price 37.95. Dealer also lists under other part numbers.

**I have found out this is the wrong thermoswitch - it runs the pump/fan
down **to 50 degrees centigrade - far too long. I believe this is an earlier
**model thermoswitch to prevent blower ops when coolant is cold - I have
found **these in the pipe that runs along the engine by the oil pressure
sensors on **earlier models. The other 2 numbers are correct. One of these
days I'll get **really bored and add the resistor pack and relay PNs for the
3 stage **cooling.

>Previously submitted:
>Dan, here is info for the Turbo/Turbo Quattro After run cooling system.
>I've included info on cooling fan operation, since the Bentley doesn't give
>much detail.
>
>The after-run cooling system for 86 up turbos and turbo quattros consists
>of a relay, thermoswitch, and an electric cooling pump. The relay is brown
>and under the dash at the aux panel. The thermoswitch is located right next
>to the upper radiator hose at the block connection, two blade connection.
>The electric cooling pump is mounted above the ABS unit, beside the injector
>cooling fan system.
>Basically, when the engine is turned off, this system runs the engine
>cooling fan at low speed and the cooling pump runs until the preset temp
>(85C) is reached.
>Additionally, this relay turns on the low speed (Stage 1) portion of the
>enginecooling fan whenever the AC is on (Bi-Level, AUTO, DEFROST) to assist
>in providing more air flow across the condensor and radiator.

>PART NUMBERS
>Relay: 447 965 571A dealer cost about 105-112.00. Blau same, Shokan 45.00
>used plus shipping.
>
>Thermoswitch: 035 919 369S (old PN) or 054 919 369B. Dealer - 37.00, Blau
>35.76. (this is for 87 tq - other years may differ...) Dealers have a very
>hard time finding this on the microfiche.
>
>Pump: 034 965 561C Dealer - 175-186.00, Blau 160.00, Shokan used 95.00.
>Chris Semple has them for 135.00 plus shipping ($143.00). 
>
>Audi 3 STAGE COOLING SYSTEM.
>Audi provides a 3 stage engine cooling fan system via a flat, 90 degree
>resistor pack mounted in front of the radiator, down on the 'frame rail'.
>Older model resistor pack are blue anodized, newer are gold. The older
>models are prone to failure. There are also low, medium, and high speed
>relays to connect the fan to the appropriate portion of the resistor pack.
>
>Low speed (Stage 1) operates when the AC is on (some models controlled by AC
>programmer, some by after-run relay), and when the engine is turned off, as
>listed above.
>
>Medium speed (Stage 2) cycles by the setpoint of the 3 wire thermoswitch
>located in the radiator (around 92C to 85C). 
**The AC high pressure switch (in front of condensor, next to muffler) also
**controls  medium speed operation. Under high pressure it closes,
**connecting the 2nd stage relay directly to 12V via fuse S15 and bypassing
the 3 wire **thermoswitch located in the radiator.
>>
**High speed (Stage 3) Operates greater than 95-92 degree Centigrade
(depends on which one you buy). 
>High speed is not fused - direct input from the battery via the relay under
>the dash. I know of no other thermoswitch control. If there is, please let
me know.

********************************AUDI FAN******************************
EMCM(SW) Dave Head (nuclear grade electrician)
87 5KCSTQ 170K miles and now counting (after $230.00 to repair...)
1.9 bar boost (charlie spring, no shim) - @ 1.3 the shuttle launches!
Maitland FL
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