Fan runs full speed when starting

[Lostboy]

Hi folks,

I have a strange problem with my Leon Sport.

Most mornings the first time I start the engine the fans run full speed for about the first 200 yds. Then they go quiet and everything is normally ok for the rest of the day.

On also sometimes does it when I come to drive home at the end of the day but not so much.

I remember seeing previous posts from people with fans running constantly but this seems different.

Anyone any ideas on what might be wrong and what parts I need to look at replacing?

(April 2000 W - ex-Demonstrator owned from first 1000 miles in case you're wondering)

Lostboy

 

[sportbilly]

I had a similar problem which was down to the slow speed fans not working, they have to replace the fans to correct this.

 

[Ruddmeister]

Sounds like a different problem if it's only happening first thing in the morning / when the car is cold, first thing for me would be to check for Fault Codes and see if maybe it throws up something for a dodgy sensor.

 

[satilaboy]

my car rumbles quite loudly (fans?) for a good minute or so and the revs are up at 1.5, then it goes to standard and the revs go down. it does this when it's been left overnight or for a good few hours. I was told this was air being pumped to the cat (or something along those lines - forget what). My mate said he thought it was a dodgy dp but it's done that from day one. i thought this was normal???

 

[The Governor]

Interesting ly my Leon Cupra 150 has had the fan going on and off all the time for a couple of weeks - even just stopping at traffic lights for 30 seconds.

It sounds like my fan kit needs replacing, luckily I have about 6 months to go on the warranty...

I wonder what else will start playing up at the 3 year mark...

 

[tacroy]

I have had this problem when I have the wrong ecu in the car.
I had a problem with my car and had to put an audi ecu in my leon.
When you read or write to the 23fxxx eprom the same thing happens.

 

[Pabs]

my car rumbles quite loudly (fans?) for a good minute or so and the revs are up at 1.5, then it goes to standard and the revs go down. it does this when it's been left overnight or for a good few hours. I was told this was air being pumped to the cat (or something along those lines - forget what). My mate said he thought it was a dodgy dp but it's done that from day one. i thought this was normal???

thats normal. Can't explain why they do it (well more like don't know the full in's and outs) but thats perfectly normal - mines done it since day 1.

My fans however, do NOT run when i start my car.

 

[Richeh]

I think this is a known fault. I can remember reading some where that the 'slow speed' resistor blows so the fan only spins at full speed.

 

[Pabs]

I'll have to check next time i go out, but I don't think my fans switch on AT ALL on startup...

 

[scottR]

Lostboy, are you sure it's the fans? There is a pump that I think circulates warm exhaust gas to help the cat heat up when the engine is cold (can't remember what it's called - Exhaust Gas Recirculation, maybe?). Sounds a bit like a fan running, but is perfectly normal. You may notice it cutting in and out a few times at low speeds, especially from a cold start.

 

[leon7284]

I thought the fans running on start-up was linked to having the air con on??? I remember alot of post in the summer months and it was put down to the speed settings of the fan. I asked about it today in my local 'specialists' and they said that its the actual climate control modual in the car???

 

[satilaboy]

Lostboy, are you sure it's the fans? There is a pump that I think circulates warm exhaust gas to help the cat heat up when the engine is cold (can't remember what it's called - Exhaust Gas Recirculation, maybe?). Sounds a bit like a fan running, but is perfectly normal. You may notice it cutting in and out a few times at low speeds, especially from a cold start.

ahhh,

I think that might be what i'm hearing. the exhaust certainly is quite loud for about a minute or so after starting after being left overnight or for a few hours - in short, when the engine is cold. It then gets much quieter after a minute or so. When my mate heard this he said it sounded like an exhasust issue but the car has done this from the day i got it and i seem to remember someone mention the heating of the cat thing.

 

[scottR]

The noise I'm talking about does sound exhaust-related, almost as if it's blowing from somewhere near the front whle the engine is idling slightly fast.

When it goes off it tends to die away with a whistle as the pump spins down, rather than cut off immediately.

Always seems to do it from cold start, but I can sometimes hear it if I stop while the engine is still cold.

If this is what you're hearing, I'd say it's normal.

 

[Lostboy]

Thanks for all the responses. Its a bit of a mystery isn't it.

I'm now think its related to temperature as it hasn't done it at all this week having been really noticeable all through the summer. I've tried turning off the climate control and it still happened but maybe "off" on the display isn't a true reflexion of what the aircon system is doing.

To clarify though the noise is a high pitch wine sounding just like most engine fans do on a hot day.

Next time it happens i plan to leap out of the car and look under the bonnet to see which, if any, of the two fans is turning.

 

[leon7284]

Next time it happens i plan to leap out of the car and look under the bonnet to see which, if any, of the two fans is turning.

make sure you put the handbreak on!