Radiator fan

JVC · Post by **JVC** » Thu May 17, 2007 10:27 am

My radiator fan(s?) seem to be on and off all the time. They come on every minute or so for about 30 seconds. This is even from start up when the engine is cold.
If I switch off the climate control the fans stay off, then as soon as I switch the climate control back on they kick in again. The fans drop the tick over revs and make it judder. I notice that the accelerator pedal moves slightly in response to this but it does not keep the revs steady. Is this normal?.

bigdaddycain · Post by **bigdaddycain** » Thu May 17, 2007 10:44 am

I dunno if its normal with climate control JVC... my bongo only has regular aircon,and the revs rise slightly as the aircon is switched on when ticking over, i beleive that to be normal,as my other cars behave in the same manner.

The fans only kick in on mine as and when the engine is hot enough,the aircon doesn't or shouldn't have any bearing on the fans as far as i'm aware...

neilfraser · Post by **neilfraser** » Thu May 17, 2007 12:19 pm

I'm not an expert on this so take the following with a pinch of salt.

There are two radiators under the Bongo bonnet. One is the radiator for the cooling of the engine using regular water and anti-freeze. This will have a temperature activted fan that will come on if the engine temp rises. If it is coming on when the engine is cold you have a problem - proba sensor?

The other (smaller I think) radiator is for the aircon units. I suspect this has it's own fan to remove excess heat from the aircon gas before it's recompressed to be be re-used.

When the aircon/climate control is on the fan may well switch on and off a lot but this could indicate that your aircon system needs re-gassing? Just a guess!

Apologies if you already understood all that. Perhaps a Bongo mechanic would like to chip in at this point??!!

Neil

Vanmanerik · Post by **Vanmanerik** » Thu May 17, 2007 12:23 pm

You may have air in your cooling system, check coolant level and bleed your cooling system.

The switch for the rad fan is high up on the cylinder head so if the fan is switched on it is a sign the head is hot, probably because the coolant has an air lock stopping it from flowing around the head.

Hope this helps.

JVC · Post by **JVC** » Thu May 17, 2007 1:27 pm

Thanks for the quick replies.
Its the radiator at the front just behind the grille. There are two fans on it. I don't know where the aircon radiator is but this is quite big and looks like the engine radiator to me.
Just checked it again, and if the climate control (CC) is on, the fans click in and out regularly, if the fan is running and I turn off the CC the radiator fan turns off too! There is definitely a link there somehow.

mikeonb4c · Post by **mikeonb4c** » Thu May 17, 2007 2:08 pm

I would guess (but its only a guess as I'm not a techie) that the rev drop is caused by the aircon having a pump/compressor and the required to turn it over on a mechanical belt drive. This would be consistent with the reason that MPG drops when aircon/climate control is in use. The accelerator moving thingie is intended to offset this by juicing the engine a bit but I imagine it would have to be adjusted just right for you to notice no difference. My aircon pump switches in and out constantly (maybe 1 min on 1 min off) when engine on tickover.

The fans - and again I'm guessing - are electric, not mechanical / belt drive from the engine. There is a main radiator cooling fan, like all cars, and a scavenger fan in the engine compartment to keep all the gubbins in there cool as there isnt sufficient induced airflow to do it otherwise. I'm not sure I've ever heard my scavenger come on, but I do recall reading on BF thats normal as - unsurprisingly - it is only likely to come on on hot days and/or when stuck in a traffic jam with no air flowing around the vehicle. I'm always a little concerned though whether the scavenger sensor, which appears to be triggered infrequently, doesnt go AWOL through lack of use.

With both electric fans,, I can see a situation where sensors etc. could malfunction and cause erratic switching.

Now - I'll prepare to get shot down by the techies before they assume their rightful role as masters of the Bongo skies and give you a correct answer!!.

behavedave · Post by **behavedave** » Fri May 18, 2007 12:27 pm

I have conventional A/C and my fan(s) also switch on and off regularly when the A/C is on, even with a cold engine. I assumed, as Neil says, that it is to remove excess heat from the A/C condensor. I first noticed it when I was regassing the system (with a Halfrauds aerosol). With low gas, there was no sign of life in the system at all. The pump was not engaging and there was no cold air. Part way through regassing, with everything running, as the pump kicked in the fans behind the radiator also kicked in at the same time. I did notice that the more gas that went into the system the less time the fans stayed on.

Dave

mikeonb4c · Post by **mikeonb4c** » Fri May 18, 2007 1:05 pm

Do the fans have a way of responding to a sensor that says the engine is taking on a greater load and will therefore be requiring more cooling?

JVC · Post by **JVC** » Fri May 18, 2007 3:44 pm

I still don't understand the link between these fans and the climate control, but maybe you are right as the CC works but it operates quite strangely. It blows cool air about the same for all temperatures down to 18.5, then at 18 it goes mad and blows lots of cold air. Does this mean I need it re-gassing. If so this may help with the fans (still no idea why though

)

dandywarhol · Post by **dandywarhol** » Fri May 18, 2007 4:47 pm

Mine's not CC JVC but the fans kick in when the aircon is used - seems normal, maybe cos the engine is labouring a bit more when the compressor is being used???

Sound like you should have your aircon regassed if it cuts in and out regularly........

bigdaddycain · Post by **bigdaddycain** » Fri May 18, 2007 5:08 pm

Should my fans be kicking in then dandy? Ive not had the bonnet up to physically check,but i cant hear them on start up...

JVC · Post by **JVC** » Fri May 18, 2007 10:14 pm

I can tell when the fans kick in, you can feel them, and it does make the tick-over slow down slightly. I think my tick over is too low anyway, it feels a bit shaky when stood in traffic, and then when the fans come on it gets worse. If I knock it into N then it gets slightly better. From memory I think it ticks over at about 800 rpm without the fans on.
Runs fantastic when on the move though

Radiator fan

Radiator fan

Fans on