B8 S4 DIY Radiator Fan Replacement How-To

[maksym]

Didn’t see this discussed earlier, so going to make a short post based on my recent experience. Might update later with more details.

The basic problem is somewhat common to Audi and VW in general - each radiator fan(s) have a speed control module that sometimes goes bad, causing the fan to run non-stop even after the engine is stopped. At some point, it just runs until it kills your battery (it destroyed mine completely to a point where I needed a new battery as well). Note that the fans are connected through fusible links as opposed to normal fuses - those are to the passenger side from the “+” jump start terminal next to your windshield.

Anyhow, there is no factory replacement for the control module- you are supposed to buy a fan/controller assembly for about $1000. I did buy a $40 knockoff controller from ebay, but it had the plug harness about 1” short and the fan harness about 0.25” short- I believe it was designed for A4 or something.



I have considered splitting it, but instead went with TYC 624630 complete fan assembly from RockAuto for about $600 (it went down to $530 as of right now).


TYC is almost an exact copy. The plastic seems to have a different sheen to it, the controllers have a different style, don’t see balancing weights on the fan blades like on OEM and the bottom connector housing seems a bit different- this is important because if you ever decide to replace one of the fans with OEM, there is a chance it would not fit into TYC housing. Other than that, the connectors on TYC went on very tight - looks like they are not completely up to oem specs. The side tabs on the housing had to be a bit forced into radiator slots as well - probably a hair thicker than they need to.

Now, the replacement. Shop manual has you remove the radiator. I found there is enough clearance to do it with the radiator still on.

Basic steps are like this.
1. Remove bumper cover as you would for the service position.

https://www.youtube.com/watch?v=Z64_GH0wSrM

2. Remove the lights. For this, undo the connectors (push them in, then press down on the tab, and pull out - like most connectors on S4). Then remove one bolt holding headlight to the radiator support cross bar, one bolt holding headlight bracket to the radiator support bar, and two bolts holding headlight bracket to the crash bar. At this point, headlight should come out still attached to the bracket.

3. Pull plastic pins from the top radiator support. Remove two plastic vertical dams that sit between the radiator and crash bar - they are held in place by a few tabs that snap into the carrier. Also remove the plastic cover from the crash bar, because it’s easy to break.



4. On the bottom, the radiator sits on two rubber washers, each located in a protruding plastic thingy that looks like a long nose. Undo the screw on each of the two thingies.


5. Undo fan connectors. They are similar to headlight connectors, but have an additional red lock tab (like spark plug coils).You first pull the lock back, then push the plug in, press on the tab, and pull the plug out (we first push in because otherwise the tab sometimes get stuck).

6. Disconnect the upper breather tube from the coolant tank (like you would for the service position). At this point, radiator should be able to move forward enough to create an opening to pull the fan. The only thing that it might hit on is the upper driver side radiator coolant hose - you can push the radiator under or slide it out by wedging an old gift card between the hose and the radiator. Put a screwdriver into the hole where the pin used to be - this will prevent the radiator from sliding back.



7. At this point, you should be able to pull the fan out. There are two tabs on each side. The bottom ones are fixed by retaining tabs - just push on them and slide the fan up. Once it is free, you should be able to wiggle it through the top.


I should disclose that I was doing this with the crash bar bolt removed and the carrier in the service position. I also had the bolt removed from the driver’s side carrier support bracket. However, I think it actually made things worse, since the maximum clearance between the radiator and the carrier top is when you are holding the carrier back on the frame.

Torques:
Bumper to fender rear 10mm bolts - 4Nm
Bumper top bolts 1.5Nm
Bumper cover bottom cover bolts - 1.5 in the front, 3mm in the back
Headlight bracket upper bolt 8Nm
Headlight to carrier bolt - 4.5Nm
Headlight to bracket bolts (though you don’t need to remove them if taking out with the bracket) - 4.5Nm
Top Carrier to frame bolts (if going into service position) 10Nm
Vertical impact bar bolts 20Nm
Horizontal crash bar bolts(if going to service position)-30Nm
Bottom radiator support bolts - 5Nm
Fan cowl to fans bolts (just in case) - 4.5 Nm


Sent from my iPhone using Tapatalk

[webbyboy]

Didn’t see this discussed earlier, so going to make a short post based on my recent experience. Might update later with more details.

The basic problem is somewhat common to Audi and VW in general - each radiator fan(s) have a speed control module that sometimes goes bad, causing the fan to run non-stop even after the engine is stopped. At some point, it just runs until it kills your battery (it destroyed mine completely to a point where I needed a new battery as well). Note that the fans are connected through fusible links as opposed to normal fuses - those are to the passenger side from the “+” jump start terminal next to your windshield.

Anyhow, there is no factory replacement for the control module- you are supposed to buy a fan/controller assembly for about $1000. I did buy a $40 knockoff controller from ebay, but it had the plug harness about 1” short and the fan harness about 0.25” short- I believe it was designed for A4 or something.



I have considered splitting it, but instead went with TYC 624630 complete fan assembly from RockAuto for about $600 (it went down to $530 as of right now).


TYC is almost an exact copy. The plastic seems to have a different sheen to it, the controllers have a different style, don’t see balancing weights on the fan blades like on OEM and the bottom connector housing seems a bit different- this is important because if you ever decide to replace one of the fans with OEM, there is a chance it would not fit into TYC housing. Other than that, the connectors on TYC went on very tight - looks like they are not completely up to oem specs. The side tabs on the housing had to be a bit forced into radiator slots as well - probably a hair thicker than they need to.

Now, the replacement. Shop manual has you remove the radiator. I found there is enough clearance to do it with the radiator still on.

Basic steps are like this.
1. Remove bumper cover as you would for the service position.

https://www.youtube.com/watch?v=Z64_GH0wSrM

2. Remove the lights. For this, undo the connectors (push them in, then press down on the tab, and pull out - like most connectors on S4). Then remove one bolt holding headlight to the radiator support cross bar, one bolt holding headlight bracket to the radiator support bar, and two bolts holding headlight bracket to the crash bar. At this point, headlight should come out still attached to the bracket.

3. Pull plastic pins from the top radiator support. Remove two plastic vertical dams that sit between the radiator and crash bar - they are held in place by a few tabs that snap into the carrier. Also remove the plastic cover from the crash bar, because it’s easy to break.



4. On the bottom, the radiator sits on two rubber washers, each located in a protruding plastic thingy that looks like a long nose. Undo the screw on each of the two thingies.


5. Undo fan connectors. They are similar to headlight connectors, but have an additional red lock tab (like spark plug coils).You first pull the lock back, then push the plug in, press on the tab, and pull the plug out (we first push in because otherwise the tab sometimes get stuck).

6. Disconnect the upper breather tube from the coolant tank (like you would for the service position). At this point, radiator should be able to move forward enough to create an opening to pull the fan. The only thing that it might hit on is the upper driver side radiator coolant hose - you can push the radiator under or slide it out by wedging an old gift card between the hose and the radiator. Put a screwdriver into the hole where the pin used to be - this will prevent the radiator from sliding back.



7. At this point, you should be able to pull the fan out. There are two tabs on each side. The bottom ones are fixed by retaining tabs - just push on them and slide the fan up. Once it is free, you should be able to wiggle it through the top.


I should disclose that I was doing this with the crash bar bolt removed and the carrier in the service position. I also had the bolt removed from the driver’s side carrier support bracket. However, I think it actually made things worse, since the maximum clearance between the radiator and the carrier top is when you are holding the carrier back on the frame.

Torques:
Bumper to fender rear 10mm bolts - 4Nm
Bumper top bolts 1.5Nm
Bumper cover bottom cover bolts - 1.5 in the front, 3mm in the back
Headlight bracket upper bolt 8Nm
Headlight to carrier bolt - 4.5Nm
Headlight to bracket bolts (though you don’t need to remove them if taking out with the bracket) - 4.5Nm
Top Carrier to frame bolts (if going into service position) 10Nm
Vertical impact bar bolts 20Nm
Horizontal crash bar bolts(if going to service position)-30Nm
Bottom radiator support bolts - 5Nm
Fan cowl to fans bolts (just in case) - 4.5 Nm


Sent from my iPhone using Tapatalk

It's not true that you can't buy the fan control module alone. Look up for the part number 8K0959501G or 8K0959501H (latest revision).

[maksym]

It's not true that you can't buy the fan control module alone. Look up for the part number 8K0959501G or 8K0959501H (latest revision).

Have you tried putting 8K0959501H in? It does not look like the right part for my car at least - mine has two models, each with long wires. The 8K0959501H looks like a single module that controls two fans at once and has shorter wires, indicating it routes to a harness in a different spot of the bumper. It does look like it fits B8 A4 though.