Engine fan

[Dan T]

Hi all,

Got a couple of questions about the engine fan..

1) It only runs when the ignition is on - is that normal? From past experience (cars!) the fan continues to run until the engine has cooled down, but on my Freda it switches off with the ignition. If I then turn the ignition straight back on, the fan starts up again.

2) Should the fan be coming on routinely after a short drive (5miles) into town? The temp gauge is reading just below the 12 o clock position and there are no signs of overheating etc.

Thanks in advance

[francophile1947]

My fan rarely comes on (unless I'm using the aircon, when the fan is always running) and certainly not after a short run of only 5 miles, so I've no idea if it goes off with the ignition. If the engine compartment is too hot, the scavenger fan works without the ignition.

[g8dhe]

The three relays that control the fans are all switched by the ignition circuit, only the scavenger fan can operate without the ignition being on.

[missfixit70]

Have you got the ac switched on, this will result in the rad fan/s being on all the time, otherwise it may be worth checking the fan sensor above the starter motor under the drivers seat.

[Northern Bongolow]

mines just started doing this,rad fans on,temp gauge below 12 oclock with mason modified gauge.not normal for moded gauge,so mazda genuine fan switch and temp sender ordered last week.will post this week as to outcome.system has been checked/bled and no air was found,
if your gauge is not modified it could mean you have problems

[Dan T]

Thanks all... Air con isn't on so will check sensors etc and let you know the outcome.

[helen&tony]

Hi
To check the scavenger fan, pull the plug off the sensor by the drivers seat (under the centre console), and short the plug with a paperclip or bit of wire with the ignition on (mine only works with ignition on)...fan goes on.
Plug it back in, and play a salon -type hairdryer( hot one), on the sensor....after a few minutes the sensor will switch the fan on...but you must get the sensor hot.
The radiator fans will go on and off with the aircon. on according to a switchable sensor I have on mine, unless , of course, the engine it hot.
After parking in hot weather for a short while, the scavenger fan MAY go on , but will shut off when you travel 1-2 Km at 30- 40 KPH , as the scavenger fan is only there to flush out hot air rising in the engine bay , which is normally refreshed in motion , by the forward speed...it is only likely to switch the scavenger fan on in slow traffic on a very hot day.
Where I live, we get very hot summers, and I've only had the scavenger fan cut in rarely, after parking.
Cheers
Helen

[Hippotastic]

Hi
To check the scavenger fan, pull the plug off the sensor by the drivers seat (under the centre console), and short the plug with a paperclip or bit of wire with the ignition on (mine only works with ignition on)...fan goes on.
Plug it back in, and play a salon -type hairdryer( hot one), on the sensor....after a few minutes the sensor will switch the fan on...but you must get the sensor hot.
The radiator fans will go on and off with the aircon. on according to a switchable sensor I have on mine, unless , of course, the engine it hot.
After parking in hot weather for a short while, the scavenger fan MAY go on , but will shut off when you travel 1-2 Km at 30- 40 KPH , as the scavenger fan is only there to flush out hot air rising in the engine bay , which is normally refreshed in motion , by the forward speed...it is only likely to switch the scavenger fan on in slow traffic on a very hot day.
Where I live, we get very hot summers, and I've only had the scavenger fan cut in rarely, after parking.
Cheers
Helen

Thank you for this, I was wanting to check my fans work when they should, and I can go and test them this weekend with this information. Nice and clear, thank you.

[dandywarhol]

Here's one for you to ponder - the fans have a mind of their own sometimes, coming on even if the engine coolant temp. is ok. I reckon the fans come on if the gearbox oil starts to overheat through hard work - the autobox oil cooler is in the bottom of the radiator and the fans help take temperature from the 'box oil through the cooled radiator coolant.

[missfixit70]

I keep thinking I have the fans sussed & then they do sumat wierd. You could be right on the 'box, according to the manual there are three measured temperature points on the ATF temp signal, 10, 40 & 80 degrees, I reckon 40 degrees is lock up temp & 80 could be fan/s on? I measured the gearbox temp after a normal run a couple of weeks back & max temp was around 70, so it would make sense that it would kick the fans in before it got too hot? apart from anything if the engine temp wasn't high enough to have the stat open to have decent flow over the oil cooler, you'd want to stop it boiling the bottom of the rad?

[dandywarhol]

Don't see it boiling the bottom tank coolant - the bottom tank rarely gets warm so it'll help keep the 'box oil cool

[Northern Bongolow]

my fan switch was faulty when i removed it today,the plastic end had nearly broken off,obviously giving dodgy signals.
the best way i have found to test the fans is,
starting from a warm engine, gradually build up the temp by reving the engine,if everything is working well the fans should come on just before the line at H then pull down the temp to approx 12oclock.

dan you dont say whether you temp gauge is modified or standard,unless ive missed it.

dandy i was discussing with kirsty the other day if the fans were linked into the oil pressure switch on the engine,is it infact an oil temp switch also.

[mikeonb4c]

If the engine compartment is too hot, the scavenger fan works without the ignition.

That's interesting, because mine doesn't. Its very rare it comes on at all but a lot of driving in traffic these last few hot days did trigger it. BUT not until the key was put in the ignition and turned to the driving position i.e. it seems only intended to come on while driving. Mines a '95 Bongo and maybe later models are different?

[g8dhe]

The wiring diagrams appear the same, power for the fan itself is NOT via the ignition switch, but the ECU controls the relay that operates the fan. Until we have a circuit for the ECU itself and then most likely we will need the program software as well then its not possible to say just what can have an affect on fan operations.

[francophile1947]

If the engine compartment is too hot, the scavenger fan works without the ignition.

That's interesting, because mine doesn't. Its very rare it comes on at all but a lot of driving in traffic these last few hot days did trigger it. BUT not until the key was put in the ignition and turned to the driving position i.e. it seems only intended to come on while driving. Mines a '95 Bongo and maybe later models are different?

Perhaps it's something to do with the way your override switch is wired My 95 worked without the ignition on