Overheating!

[marcman]

I've got a 1.4se 16v

A few weeks ago, on a very hot day, while sat in traffic, my temperature warning light came on. I checked the temperature dial and it was way into the red. I turned off the air-con, opened the windows and turned the hot air on full blast. It cooled the engine off quite quickly and once I finally got on the motorway I put the air-con back on and the temp remained stable.

I've checked the coolant level - it's fine. The car hasnt overheated since so I havent yet looked into it any further. Im thinking maybe the radiator fan wasnt cutting in when supposed to. How do I check that the fan is working correctly? When exactly should it be coming on?

I've read that Golfs have a problem where the fan doesnt come on when the air-con is running. Could this be happening on my Polo? Anybody else had a similar experience?

Cheers in advance
Marcman

[Kristof_clg]

To check if it is working, the fan should come on when you drive for a while and then turn the ignition off (when you park, for example).

[jonnopolo]

I've found that my fan only comes on when the car's stationary; when the fan does cut in, the temperature gauge never goes above normal. My wife's MK4 is the same. Maybe an idea to check the fuse for the fan hasn't blown or isn't missing altogether.

[alexperkins]

Temp control valve in the rad may have seized

Or possible, you temperature sender is bust and the engine isnt thinking its hot, therefore not cooling appropriately

[shantybeater]

my bet is coolant temp sensor or radiator fan, make sure you check the fuses although its unlikely as the AC is on the same fuse (although my cupra had this exact problem & the air con was working)

not sure if its the same for the polo but with cupras Fuses are known to melt or blow when the air con is being used as well as the fans because of the large amount of current being used on the same fuse , you might just need to clean the connections or replac it

jonno - obviously the reason you mainly only notice the fans coming on when stationary is because this is the time the engine isnt able to cool itself, when on motorways etc.. usually the cool air is enough to keep things stable

[jonnopolo]

jonno - obviously the reason you mainly only notice the fans coming on when stationary is because this is the time the engine isnt able to cool itself, when on motorways etc.. usually the cool air is enough to keep things stable

Yes indeed.

[Enzo]

Fuses are known to melt or blow when the air con is being used as well as the fans

That stritcty cant be right... cos as soon as you turn the aircon on the radiator fan should come on aswell to help draw air throught the aircon rad at the front!

So there is no actual way of having the aircon on without the rad fan.

Infact thats probably a good way to test the fan works... simply stick the aircon on... obviously it wont tell you if the switch in the back or the rad is working or not, but you will know the fuse and the fan both work.

[marcman]

Right, i've finally had time to look at this problem a little more.

Seems the radiator fan itself is actually working. If I turn the aircon on then the radiator fan comes on too (as I belive it should). If I remove the red fuse on the battery compartment, with the ignition off, then the fan comes on (don't know what this means).

The engine overheated again a couple of weeks ago and I still suspect that the fan isnt cutting in when it's supposed to. Any ideas on the cause of this? What do I need to do next?

Whiles it's not a massive problem - it's only overheated twice, always on hot days, in traffic and very easy to cool off again by just blasting the hot air on for a few minutes - I would still like to get to the bottom of the problem.

Thanks in advance for any suggestions...

[DanOliver]

Surely if its not cutting in when it should be the sensor is knackered? Just a guess really, but what else could it be if the fuses are in tact and the fan works?

[marcman]

Surely if its not cutting in when it should be the sensor is knackered? Just a guess really, but what else could it be if the fuses are in tact and the fan works?

Yeah, probably is but I don't have a clue where the sensor is or how to change it, though I'm certainly not adverse to having a go

Another thread also mentioned that if the fan comes on when the fuse is removed then the relay is at fault. Again, I don't know where this relay is.

[DanOliver]

Have you got a haynes manual? Might have all the info you need in there? Mines probably a different version to yours..