Rad fans not coming on

[thegreenman]

I have just noticed myrad fans don't come on under normal driving conditions.
Removed the connector from the temp sensor and they fire up OK
I am assuming a sensor fault, but can't see a replacement part in the shop section

Does anyone know where I can get a new temp sensor?

TIA

[francophile1947]

They won't come on until the engine is getting too hot - I've very rarely had mine come on and I am not overheating

[mikexgough]

Mazda do them if course and so do the usual Bongo spares suspects....Mazda package the Denso 179700 0220 up as O.E
Jas shows the fitment on their site
I replaced mine, a) my fans rarely run like Franco's and b) the plastic socket on the end of the sensor was looking aged so for me worth the cost to change......needless to say after I had changed the sensor, I ran the engine to the point where the double speed fans run...to check it out....

[Northern Bongolow]

to test the switch remove it carefully, and watch out for the ally sealing washer.(the grey plastic end breaks off,or at least can be loose) use a deep socket. when placed in water it should be open(no flow of current through) when the water gets to approx 96 deg c the switch should close (circuit).
this switch also controls the fast idle on/off, and the glow plug info to the ecu so needs to be in good condition so a good quality replacement should be used for such a key component imo.

[crazy uncle gray g]

You probably haven't got a problem as John says
another way to test is to run her up on your drive for 45mins
with the heaters off, watch your temp gauge and you should find
that with no rushing air flow through the rad the fans will kick in
of course you'll need diesel in the tank for this method

[brorabongo]

You can also quickly test to see if the fans work by disconnecting the sensor....

http://www.igmaynard.co.uk/bongo/forum/ ... gy#p378116

[thegreenman]

thanks all, pretty sure it has failed. Fans come on when I disconnect it. Will remove it for testing asap.

[widdowson2008]

Agree with John and crazy uncle gray g. Fans will only come on when the stat has lost control (96 deg.C), so if your system is OK, then you will probably never hear them (unless you have the aircon running).

[Northern Bongolow]

thanks all, pretty sure it has failed. Fans come on when I disconnect it. Will remove it for testing asap.

dont forget you will have to bleed the coolant system if you remove it to test it.

[missfixit70]

If the switch fails, ie open circuit, the fans stay on permanently, so as has already been repeatedly repeated, yours is probably fine
Rad fans should not come on during "normal" driving conditions. If you were stuck in traffic for more than 20 minutes with the engine running, you might expect them to kick in, or if you were going really slowly/heavily loaded up a steep hill mebe where there would be insufficient airflow across the rad to cool the coolant going through it. That's assuming of course that your stat is doing its job ok

[mikexgough]

thanks all, pretty sure it has failed. Fans come on when I disconnect it. Will remove it for testing asap.

If your sure or suspect it has failed....just replace it.....don't waste time testing it....

[teenmal]

thanks all, pretty sure it has failed. Fans come on when I disconnect it. Will remove it for testing asap.

If your sure or suspect it has failed....just replace it.....don't waste time testing it....

Just test the new one

[mikeonb4c]

If the switch fails, ie open circuit, the fans stay on permanently, so as has already been repeatedly repeated, yours is probably fine
Rad fans should not come on during "normal" driving conditions. If you were stuck in traffic for more than 20 minutes with the engine running, you might expect them to kick in, or if you were going really slowly/heavily loaded up a steep hill mebe where there would be insufficient airflow across the rad to cool the coolant going through it. That's assuming of course that your stat is doing its job ok

Waheyyyy - she's back

[widdowson2008]

If the switch fails, ie open circuit, the fans stay on permanently, so as has already been repeatedly repeated, yours is probably fine
Rad fans should not come on during "normal" driving conditions. If you were stuck in traffic for more than 20 minutes with the engine running, you might expect them to kick in, or if you were going really slowly/heavily loaded up a steep hill mebe where there would be insufficient airflow across the rad to cool the coolant going through it. That's assuming of course that your stat is doing its job ok

Waheyyyy - she's back

Yep. Good innit?

and this may explain fan operation
http://www.igmaynard.co.uk/bongo/forum/ ... =3&t=48872