Cooling Fan not kicking on FSI

Dean

Member
Hi all,
Engine running fine but on summer day in traffic, going into security mode and need to wait 20 minutes to restart.
Temperature goes to 90 and stay there.
Fan works to 1st speed when air con on.
Any ideas? Thanks in advance
 

andrewparkeruk

A2OC Donor
I’m not familiar with “security mode” and having to wait to restart.
My car was overheating i.e. “boiling over” (even though temp gauge never went above 90°) which was traced to the radiator fan failing to run at the second, higher speed. My garage has replaced the thermostat, radiator hose fan sensor or radiator fan control unit. I have had all items replaced (in that sequence) on my car; still not 100% sure the issue is resolved.

Andrew
 
Last edited:

Dean

Member
I’m not familiar with “security mode” and having to wait to restart.
My car was overheating i.e. “boiling over” (even though temp gauge never went above 90°) which was traced to the radiator fan failing to run at the second, higher speed. My garage has replaced the thermostat, radiator hose fan sensor or radiator fan control unit. I have had all items replaced (in that sequence) on my car; still not 100% sure the issue is resolved.

Andrew
All this items seems to be fine. I believe there is a connection not done somewhere. This is happening since the air con compressor has been changed, was working fine before.
 

andrewparkeruk

A2OC Donor
The air con drives the fan at the first speed. When mine was ”broken”, I managed the situation by running the car on air con, rather than opening the OSS.
In my limited knowledge, the fan running at second speed is governed by both the radiator hose fan sensor / radiator fan control unit.
 

Dean

Member
The air con drives the fan at the first speed. When mine was ”broken”, I managed the situation by running the car on air con, rather than opening the OSS.
In my limited knowledge, the fan running at second speed is governed by both the radiator hose fan sensor / radiator fan control unit.
Fan control unit is fine, maybe the fan sensor then, where is it located?
 

andrewparkeruk

A2OC Donor
I have no idea; a garage does all of the work on my car. I simply have a list of all the parts we replaced to try to fix the issue
PS there may be a clue in the part name: radiator hose fan sensor
 

Dean

Member
I have no idea; a garage does all of the work on my car. I simply have a list of all the parts we replaced to try to fix the issue
PS there may be a clue in the part name: radiator hose fan sensor
I came across a thread which had similar issue and found out the air con pressure was playing a part with those symptomes. I believe it is related as had no issue until the air con compressor been replaced from a garage who had no clue about the complexity of the Fsi.
 

Dean

Member
Ok it appears that the signals come from the aircon control panel, only when the engine temp is above 95 will the fan go to stage 1 then 102 it will go to stage 2, even today my engine sat at 90 so that's why it is not running when ticking over. It will not start when you turn on the aircon if the gas is not at pressure! It could simply be a low gas pressure then!

Does anyone have a wiring diagram / current flow diagram as audi call it!
 

audifan

A2OC Donor
I "think" there is three speeds to the fan. Speed 1 air con on fan low. Speed 2 air con on engine over about 95 medium speed and speed 3 temp about 102 fan runs on high speed. I run ac all year round and even in summer second speed never came on (tdi 75). But you say the fan runs on slow when ac is on but does not speed up. I would replace the temp sensor and the thermostat and flush through the coolant. Good chance the coolant has not been replaced when it should have been. Make sure you refill with the correct G12, G12+, G12++ or G13 either premixed or diluted correctly and never mix coolants.
If fan runs slow when ac is on (not ECON) the ac is working, may be low on gas but do not think that is an issue.
 

audifan

A2OC Donor
From what I can see the FSI has the combined double coolant sensor which supplies the dash and the ECU. They feed into the Motronic controller J220 along with the F51 thermal switch for coolant circulation. The J220 gives info to the J293 Radiator fan control unit. So perhaps F51 or the fan control unit itself is faulty. At this point I'll hand over to some of our resident FSI experts.
 

Andrew

A2OC Donor
Ok it appears that the signals come from the aircon control panel, only when the engine temp is above 95 will the fan go to stage 1 then 102 it will go to stage 2, even today my engine sat at 90 so that's why it is not running when ticking over. It will not start when you turn on the aircon if the gas is not at pressure! It could simply be a low gas pressure then!

Does anyone have a wiring diagram / current flow diagram as audi call it!
Hi,

It sounds like the 90°C you are referring to is from the dash, do not believe it!!! It is is more for reassurance of the driver that the coolant temperature is within acceptable range, more like a comfort display, akin to a baby's dummy. The dash temperature gauge is designed to be stable at 90°C even though with your FSI, (once warmed up and assuming all is well), it will be somewhere bewteen 105°C - 110°C fluctuating continuously to some extent, in fact your dash temperature will not rise above 90°C until the coolant temperature is somewhere > 110°C. Do not reach any conclusion based on the dash temperature gauge, you need to monitor it with VCDS for the true picture.

I will PM the wiring diagram you request.

Andy
 

Dean

Member
Th
From what I can see the FSI has the combined double coolant sensor which supplies the dash and the ECU. They feed into the Motronic controller J220 along with the F51 thermal switch for coolant circulation. The J220 gives info to the J293 Radiator fan control unit. So perhaps F51 or the fan control unit itself is faulty. At this point I'll hand over to some of our resident FSI experts.
Thanks, the fan control unit is fine, gonna start with the J220 then...
 
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