Low Level Flyer Posted October 15, 2018 Report Share Posted October 15, 2018 Hi All, So I recently noticed that the Engine Compartment Fan seems to be coming on a lot more than it used it - had the car about 18 months now (could understand it if it was a really hot day or if I'd been sat in stop start traffic a considerable amount of time but it's currently only 9 degrees Celsius outside). The car seems to be running absolutely fine other than this so I'm suspecting an ambient temperature sensor might be faulty but was wondering if anyone had any previous experience of such an issue? (It's a 2007 3.4 S) Any advice would be very much appreciated! Link to comment Share on other sites More sharing options...
toplad Posted October 15, 2018 Report Share Posted October 15, 2018 Have you noticed any change the temp gauge? Link to comment Share on other sites More sharing options...
Low Level Flyer Posted October 15, 2018 Author Report Share Posted October 15, 2018 Doesn't rise any quicker than normal from cold and sits comfortably at the 12 O'Clock position when up to temperature. I've got a iCarsoft POR 2 diagnostic scanner (bought it not long after I got the car due to a recurring issue that turned out to be a knackered catalytic converter) - could always plug it in and take the car for an extended drive to get an accurate idea of what's going on - any ideas what the normal T's and P's might. Link to comment Share on other sites More sharing options...
dim33 Posted October 16, 2018 Report Share Posted October 16, 2018 I believe the fan comes on when the compartment temperature reaches 70 degrees and shuts off again once the temperature is down to 55 degrees. So if the compartment is not 70 degrees and your fan is on I'd have the thermostat checked. I have noticed that mine can come on if I have driven for a while and then stop for a bit with the engine off. The heat from the engine then just heats the engine compartment and the fan can come on when I restart it. It does shut off pretty quickly though once on the move again. If you have noticed a change of behaviour keep an eye on it. The fan coming on won't do any harm at the end of the day so you don't have the rush to get it checked. If the fan never came on that would be worth getting checked asap. Link to comment Share on other sites More sharing options...
Araf Posted October 16, 2018 Report Share Posted October 16, 2018 My fans have been on more than usual since the heat wave - I think the air con may be a little low on gas. Link to comment Share on other sites More sharing options...
Low Level Flyer Posted October 16, 2018 Author Report Share Posted October 16, 2018 Thanks for the responses so far. Araf - I agree I’ve noticed this more since the heat wave the other month, but if my air con was low on gas would this actually impact on the Engine Compartment Fan? (As dim33 talks about, I thought the fan only activated/deactivated based on Engine compartment temperature - don’t see why air con could impact on this, but I’m not an engineer!). I did read somewhere else about someone whose ambient temperature sensor in the engine compartment came loose and was touching the main engine block (leading of course to spurious readings). I would investigate my own car for this problem but as the fan does deactivate/reactivate I don’t think it can be the case as if it was physically touching the engine I think the fan would be on non stop from as soon as the engine hit the triggering temperature for the sensor Fan Logic. Will let you know if I discover the root cause of the issue (assuming there is an issue!) Link to comment Share on other sites More sharing options...
Low Level Flyer Posted October 16, 2018 Author Report Share Posted October 16, 2018 Drove the car again tonight and it seems I got it wrong. The fan that keeps coming on and off (a lot!) is the passenger side fan behind the front bumper and not the Engine Compartment Fan. Any ideas would be most welcome? (Have checked and there is no debris blocking the air intake and I’ve had the car fitted with Mesh to protect the radiators.) Link to comment Share on other sites More sharing options...
dim33 Posted October 16, 2018 Report Share Posted October 16, 2018 10 minutes ago, Low Level Flyer said: Drove the car again tonight and it seems I got it wrong. The fan that keeps coming on and off (a lot!) is the passenger side fan behind the front bumper and not the Engine Compartment Fan. Could it be that the driver's side fan is not working? This would cause the passenger side fan to compensate by having to do the work of both. I have come across a similar case where a small stone had blocked one fan from turning causing the exact symptoms you are describing. If the other fan is not working at all you will need to inspect it which I believe involves unscrewing the wheel arch and pulling it back a bit. See if something is blocking it from turning. Link to comment Share on other sites More sharing options...
Low Level Flyer Posted October 16, 2018 Author Report Share Posted October 16, 2018 Good suggestion! Will have a check. Link to comment Share on other sites More sharing options...
Low Level Flyer Posted October 23, 2018 Author Report Share Posted October 23, 2018 Turns out it was just a stone blocking one of the fans from turning! (amazing such a simple thing can cause a problem!) Link to comment Share on other sites More sharing options...
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