Help - VR6 cooing fans constantly on full speed

[g0ldf1ng3r 15]

Hi all

 

Am hoping someone can assist me with my VR

 

for some reason my fans have decided to play up - as soon as i start the car they kick in on full speed

 

does anyone know which of the 3 sensors works the stage 3 fans?

 

it also happened a couple of weeks ago but i disconnected the sensor nearest the top of the rad & in the radiator, the one just under where the battery is, & when i started it up the fans did not kick in

 

i reconnected that sensor & tried it again & fans didnt come on again

 

i am thinking that might be the sensor at fault but am not sure - can anyone confirm & give a part number if possible pls?

 

im off to the motor factors this afternoon having booked a half day

 

thanks

[g0ldf1ng3r 15]

looking throught the VR6 cooling guide i can see this:

 

"These are approximate as it depends on the age of the senders and how crusty they are. VAG-specified values and part numbers are listed further down.

Stage 1

Controlled by the temp sender in the rad, directly to the fans

Switch On: 92-97 C (198-207 F)

Switch Off: 84-91 C (183-196 F)

 

Stage 2

Controlled by the temp sender in the rad, combined with info from the yellow temp sender via the fan controller

Switch On: 99-105 C (210-221 F)

Switch Off: 91-98 C (196-208 F)

 

Stage 3

Controlled by the black coolant temp sender, via the fan controller

Not listed in the guide above, but it kicks in at around 110-115 C.

For non-AC cars, stage 3 should never come on under normal conditions, if it does, you have a problem.

 

Temp senders

The coolant warning light is actually a level sensor (those 2 metal spikes in the header tank are what the plug is for and measure yes/no on coolant level). There is no over-temp warning other than the gauge going up/big cloud of steam coming out of the engine bay

 

The main fan control temp sender is screwed into the radiator. This is a 3-pin brass jobber and has 2 different pin layouts depending on if you have early/late VR. It looks like early ones are all 3 pins in a row, late ones are 3 pins in a triangle shape."

 

which is implying to me that it was the main fan control temp sender i disconnected

 

i am thinking to try disconnecting that again, if fans do not come on but then do when i reconnect it i should replace that

 

can anyone give me a sanity check on that pls lol

[g0ldf1ng3r 15]

also found this from Kev

 

"Speed 3 is controlled by the black sender. As Hombre said, that and it's yellow partner are in the thermostat housing, which is on the engine block behind the fan motor. A plastic shroud covers them, which you need to pull off."

 

which is where i am at hopefully as the fans sound super loud

 

will try black sensor first

[g0ldf1ng3r 15]

anyone?

 

leaving work soon...

[dr_mat 0]

Quite often the high fans come on because you have an air lock at the top of the coolant system.. where the sensor is.

 

 

A Corrado is for life, not just for the MOT.

[g0ldf1ng3r 15]

Quite often the high fans come on because you have an air lock at the top of the coolant system.. where the sensor is.

 

 

A Corrado is for life, not just for the MOT.

 

thanks

 

i did follow the coolant top up procedure after i replaced the radiator elbow a few weeks ago but will add it to the list to check

[fendervg 33]

I'd say replace the black coolant sensor followed by the radiator temp sender in that order.

[g0ldf1ng3r 15]

ok ive done some testing

 

unplugged the black temp sensor & fans still on as soon as ignition is turned on

 

unplugged fan controller & no fans with ignition

 

unplugged temp sender in rad, no fans, plug back in & fans on

 

so, my question is how do i determine if it is the fan controller or the temp sender in the rad? anyone have any ideas?

 

i think i read a post from Kev saying that if the black sensor is unplugged & fans still come on with ignition then it is the fan controller - ?

 

thanks

Edited November 27, 2017 by g0ldf1ng3r

[fla 9]

If you can get a meter across the pins of the black sender you'll know if its working. When cold it shoukd have high resistance - basically open circuit.

[g0ldf1ng3r 15]

more testing

 

with all 3 temp sensors unplugged the fans still come on

 

with those 3 connected, if i unplug the rad sender the fans do not come on

 

re-reading Kev's post - "Try disconnecting the senders with the fan running and see which one stops them. Radiator sender, then Yellow temp sender. If they're still going with those disconnected, it will be a faulty fan controller box."

 

which is pointing me to the rad temp sender

 

as if it was the controller the fans would still come on with the rad sender disconnected, which they do not

 

sanity check pls lol

 

?/?

[Jim Bowen 1]

I would say its the rad sensor, also the cheaper/easiest thing to try first, i heard the fan controllers can be hard to get hold of. My car has done about 230,000miles and the rad sensor has failed before, but still the original fan controller.

 

Make sure you fit a new seal on the rad sensor, my leaked and had to remove it and refit, which means losing coolant.

 

I don't even have a black sensor in the thermo-housing, i cut it off by mistake :lol:

[Darren Wilkerson 10]

Hi everyone, unfortunately I can't help you with the problem, but everytime something brakes on my Corrado I spent weeks playing gessing games on what was the reason (talking about electrical parts). It teached me one thing - go use that ODB port to diagnose the problem. It will save you time and get your Corrado up and running faster.

[fendervg 33]

Unfortunately the OBD will not help in diagnosing the radiator fan switches or control module - it will only check the blue ECU coolant temp sensor. I'd say replace the senders first, they will be cheaper than a fan control module.

[g0ldf1ng3r 15]

thanks to all for taking the time to reply

 

i have a new rad temp sender on its way from heritage

 

hope it has the O ring with it though as i didnt order one

[Cressa 44]

Good luck mate. I've only just read your thread and it seems you are doing the right problem solving. Let us know how you sort it, as you will eventually

Cressa

 

Sent from my SM-G900F using Tapatalk

[g0ldf1ng3r 15]

Good luck mate. I've only just read your thread and it seems you are doing the right problem solving. Let us know how you sort it, as you will eventually

Cressa

 

Sent from my SM-G900F using Tapatalk

 

thanks m8

 

got my hands full with rado's at present - the valver sprung an oil leak on sunday, jacked it up yesterday & it seems to be coming out the top of the oil cooler (between the cast part that attaches to the block & the metal cooler) so going to try changing the O ring on that first

 

queue new post asking how to take the cooler apart lol

[g0ldf1ng3r 15]

thanks to all for taking the time to reply

 

i have a new rad temp sender on its way from heritage

 

hope it has the O ring with it though as i didnt order one

 

spoke to Heritage - temp sender does come with the gasket o ring, phew lol

[robrado974 1]

I was just about to say it does come with the ‘o’ ring .

[g0ldf1ng3r 15]

I was just about to say it does come with the ‘o’ ring .

 

winner, thanks rob :)

[VR-OOM 0]

My fans ran on even with the engine off, I had to disconnect the fans to stop the battery from going flat. I changed all the temp sensors inc the rad to no effect, in the end it turned out to be the fan control module.

[Cressa 44]

What's the part number on your fan controller. Only asking as someone may have a spare you could try. My car isn't moving so you could try that (posting) but I'm sure someone will be more local to you

Cressa

 

Sent from my SM-G900F using Tapatalk

[g0ldf1ng3r 15]

What's the part number on your fan controller. Only asking as someone may have a spare you could try. My car isn't moving so you could try that (posting) but I'm sure someone will be more local to you

Cressa

 

Sent from my SM-G900F using Tapatalk

 

thanks for the offer cressa, much appreciated

 

i got the new rad sender fitted yesterday afternoon & when reconnected i now do not have fans when i turn the ignition on

 

i did the coolant top up procedure to rid any air locks but managed to not loose much coolant during the sender swap

 

thermostat worked as it should but when i let the engine run until water temp got to where i thought fans should kick in but no fans - odd!

 

water temp got to not far off 110 & i shut off as a just in case - fans came on for over run as you would expect

 

thus im now not sure if it is a dodgy sender

 

temp didnt get to the point you would expect fans to kick in on way to work this morning so going to have to check & test over coming few days

 

will also check i reconnected the yellow switch ok in the stat area

[robrado974 1]

thanks for the offer cressa, much appreciated

 

i got the new rad sender fitted yesterday afternoon & when reconnected i now do not have fans when i turn the ignition on

 

i did the coolant top up procedure to rid any air locks but managed to not loose much coolant during the sender swap

 

thermostat worked as it should but when i let the engine run until water temp got to where i thought fans should kick in but no fans - odd!

 

water temp got to not far off 110 & i shut off as a just in case - fans came on for over run as you would expect

 

thus im now not sure if it is a dodgy sender

 

temp didnt get to the point you would expect fans to kick in on way to work this morning so going to have to check & test over coming few days

 

will also check i reconnected the yellow switch ok in the stat area

 

You may as well change the senders in the block as well Goldie .

 

 

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[g0ldf1ng3r 15]

You may as well change the senders in the block as well Goldie .

 

 

Sent from my iPhone using Tapatalk

 

thanks rob

 

will do some testing & may replace them all like you say

[g0ldf1ng3r 15]

did another test on the VR on saturday

 

took her out for a run, all seemed to be well. let her warm up further on the drive when i got back & am pleased to report my fans kicked in at stage 1 as you would expect

 

job done :D