Basic fan operation

[gazza]

Thanks for that

[widdowson2008]

Hi there, I seem to have a problem with my rad fans, they come on high speed when the sensor is disconnected, but the low speed fans don't cut in when the engine gets up to temp.
Is there any way of checking the low speed rad fan circuit? Does anyone know where these rad fan relays are fitted? Thanks - Garry

May be wrong, but my understanding of fan operation and testing is:
When you disconnect the sensor, the fans will come on. This is only proving that the fans work - NOT the sensor.
What you need to find out is if the sensor is working, and I'm not sure of an easy way how to do that. Maybe someone else does????

[gazza]

Hi, thanks for the reply, had a new sensor fitted and still the same, so suspect normal fan circuit is faulty.
Garry

[missfixit70]

What temp are you expecting the low speed fans to come on at Gazza & how/where are you measuring it? Not supposed to kick in till 96 degrees at the sensor, which you'll have to push it pretty hard to reach.
To test the sensor itself,
at 20 degrees, resistance should be 2.3 - 2.6 ohms
at 80 degrees, resistance should be 0.29 - 0.34 ohms.
I guess if you removed the sensor (or use the old one if it's within range) & stick the sensor end in a boiling kettle while connected to the circuit, it should switch the fans on, not gona be that simple to do, due to the location of the wiring.
Only way to properly test it it is to run it up & get it up to temp, just needs a bit of patience, but you need to have sumat to monitor the temp with.

[gazza]

Thanks for the reply, yes the new sensor was plugged into the circuit then dropped in boiling water, but no fans.
When disconnected fans on full.

[missfixit70]

sensor needs checking then, you've already checked the fans work by disconnecting, although if you dropped the whole sensor in boiling water, it wood provide a short circuit across the terminals thus negating the action of the sensor.
You need to just immerse the sensor end in the water being careful to keep the terminals dry.

[gazza]

Thanks , but I cannot see 2 new sensors that I have tried being faulty.

[missfixit70]

Are they genuine ones? I'm not convinced they are faulty TBH, just that the method of testing them live may be faulty. Did you check the resistance as described in my post above from the manual?
As you have checked the fans work when you disconnect the plug, you've proved that part of the circuit haven't you? Only leaves the sensor as far as I can see?
Does your ac work & do the rad fans switch in & out as it loads/unloads?

[Northern Bongolow]

gazza, just need to check we are on about the correct sensor here, which sensor are you disconnecting, and which fan/s are you trying to get to work.
maybe its me(it usually is) but something doesnt smell right.

[gazza]

Hi rad cooling fans and temp sensor in the side of the head (middle) which gives the signal to the engine ECU

Thanks

Garry

[Northern Bongolow]

thats the baby, sometimes on here we get all sucked into thinking we are all on the same page when we all arnt,this time its just me .

[gazza]

Managed to damage the engine temp sensor during head change. The sensor at the front of the head which controls the temp sensor gauge on the dashboard.

Any idea of the part number and where is best to source a replacement.

Garry

[teenmal]

Managed to damage the engine temp sensor during head change. The sensor at the front of the head which controls the temp sensor gauge on the dashboard.

Any idea of the part number and where is best to source a replacement.

Garry

Hi Garry,

Your local factors should have them in stock,they fit a host of vehicles as standard....

http://cn.oemol.com/oem/en_oem_detail/4 ... ensor.html

Cheers..

[gazza]

For some reason I cannot open that link, do you have the part number , thanks

[teenmal]

For some reason I cannot open that link, do you have the part number , thanks

JE151851X