cooling fan issue...

limbo118118

limbo118118

LORD
Joined
Oct 6, 2009
Messages
526
Reaction score
58
Points
28
Location
Wrexham.. North Wales
Hi all... doing abit of work on the s3 this week and noticed a problem.

These are the symptoms..

- fans dont turn on during idle.. meaning car then overheats.

- tryed pressing a/c button to see if they activated an neither do.

- checked the 30a fuse ontop of battery an seems fine also as electric pump works fine.

- connected 12v to a fan switch near bleed valve an fan powered up fine.

Should add its had brand new water pump an thermostat within last 12 months

Any ideas what this could be? Thanks in advance!
 
Hi ive got the same issue been told to change the 2 sensors one on the coolant pipe and one on the radiator,have'nt had time to do mine yet but will post if it works
 
  • Like
Reactions: limbo118118
Fitted new fan switch today. Got car up to temperature an fans still didnt kick in... car started to boil over at just over 95degrees.. is this to low to start boiling over?

any idea whats next down the line to solve this?
 
Last edited:
So... the after run pump is working?

You have checked the fans by bridging the wiring plug for the fan sensor you have just changed?

You have checked there it voltage coming from the fuse on top of the battery?

You have checked the temps on both the engine measuring blocks and the instruments measuring blocks to make sure the readings correlate in VCDS?

<tuffty/>
 
Afterrun pump is 100% running.

Didnt bridge the too of the fan sensor i did the high speed connection below it.
But that can be done tomorrow!


Will check voltage from fuses tomorrow too but afterun pump an fans go off same fuse dont they?

An will check on vagcom too. I just used liquid gauge today.

Changed sensor- filled water- cap off- heaters on - then after while turned heaters off. An watched temp get up to 95+ at which point water started to just reach top off expansion bottle an bubble out..
 
hummm... thats odd... not had one boil over at 95-100... normally run up on first start with the cap off and on occasion have to bleed the system off a bit by undoing the drain tap on the bottom of the rad... does the lower hose get hot? I mean hot not warm...

Try running up from cold , get to 90 then drain a bit out of the bottom tap (be very careful its hot obviously)

Leave the cap off to prevent pressurisation... you will be ok as long as you don't take it to 100 and over...

After draining off (don't forget to top up the reservoir) let it cool off then try again wit the cap on...fans kick in around 96/97 on slow speed... slow speed should alos kick in straight away (all the time) if the aircon is working/on

<tuffty/>
 
I will try that tomorrow too.

I remember checking bottom hose early on an it was just warm.. but i didnt check after that when it was getting hotter..

My aircon hasnt got any gas in.. so dont think that would work.
 
Right....

Checked voltage on

-fuse ontop of battery
-fan switch

Both gave 12v..which is good.

I made sure all connections were good..

Ran car on idle up to 90° let abit of water out of bottom tap.. then refilled to correct level an put top on..

Then started car again with vagcom running

Checked bottom hose which was now hot not just warm.

On vagcom started to creep up past 95+ an temp gauge in car hadnt gone past 90 yet..

Then vagcom started going up to 100.. boths fans kicked in high speed!

Temp gauge in car was only showing 90 still..

Your thoughts lol!?
 
limbo118118 said:
Right....

Checked voltage on

-fuse ontop of battery
-fan switch

Both gave 12v..which is good.

I made sure all connections were good..

Ran car on idle up to 90° let abit of water out of bottom tap.. then refilled to correct level an put top on..

Then started car again with vagcom running

Checked bottom hose which was now hot not just warm.

On vagcom started to creep up past 95+ an temp gauge in car hadnt gone past 90 yet..

Then vagcom started going up to 100.. boths fans kicked in high speed!

Temp gauge in car was only showing 90 still..
Click to expand...

Righty... its normal for the gauge not to rise... this is so the owner doesn't suddenly think the car is over heating while the coolant temp is operating in its normal range of 90-100 degrees

Low seed should kick in at 96 ish, high speed at just over 100

From what you are saying here the low speed isn't working?

limbo118118 said:
Your thoughts lol!?
Click to expand...

Burn it :)


....or check the fans on both low and high speed from the plug to the switch (bridging between terminals, not sure of the combos off hand though) as clearly the fans now work but need to establish if the fans low speed is shot...

<tuffty/>
 
  • Like
Reactions: limbo118118
On vagcom going to 90+ is normal, you will see this on the instrument panel to under block 49c.
My high speed fans kick in high at like 102 degrees, this was tested last week during the hot weather, this soon gets it to around 97/98 which is my stationary temp after a drive. Cruising mine sits at 87-89, driving hard it will hover around 92-93.

Point is, don't be worried about actual temp readings being over 90, despite the gauge reading 90, something to do with the way the temp gauge works in that it will only record overheating when it gets far too hot.

The bubbling over of the expansion cap is weird tho
 
  • Like
Reactions: limbo118118
Righto... so if i test the bottom connections for the high speed an low speed..

Ino from other day the high speed worked fine from connecting it up

What would be the reason for low speed not kicking in at correct temp?

Thanks for the replys guys!
 
Fan control module / relay ordered be here in the morning will test that out.. if not might have to run a inline switch/relay to high fan as i need the car for next week
 
You must log in or register to reply here.

Similar threads

reno85
Cooling fan issue?
Replies
2
Views
818
reno85
reno85
G
Cooling Fan issue.
Replies
6
Views
744
Ginger9860
G
bengal
Cooling fan issue
Replies
4
Views
2K
vfr800
vfr800
D
Cooling fan
Replies
2
Views
881
jack.s
jack.s
Tonka777
Cooling fan system
Replies
12
Views
853
desertstorm
desertstorm
Top
Back