Fan won't kick in
Moderator: Robsey
Fan won't kick in
Hello guys got a little trouble the radiator fan won't kick on I checked fuse 24 30a for the fan but it's ok I replaced it with another 30a but still not working I put a positive and negitive to the fan direct from battery to test it and that seems to work any other suggestions or tips I could try thanks
Re: Fan won't kick in
Faulty thermo-switch on the radiator?
Try again, but short out the contacts of the thermo-switch.
It is on the driver's side end of the radiator - about half way down - facing towards the engine.
I use a 20 amp blade fuse with the blades twisted and inserted into the switch in the radiator.
You will probably need to trim the blades to fit into the narrower slots in the switch.
If the fan now works with the ignition on, then the thermo-switch is your culpret.
Try again, but short out the contacts of the thermo-switch.
It is on the driver's side end of the radiator - about half way down - facing towards the engine.
I use a 20 amp blade fuse with the blades twisted and inserted into the switch in the radiator.
You will probably need to trim the blades to fit into the narrower slots in the switch.
If the fan now works with the ignition on, then the thermo-switch is your culpret.
Re: Fan won't kick in
Thanks mate I took the switch plug And bridged the wires and the fan came on, I then took the radiator switch out the radiator cleaned the contacts and sprayed a little wd-40 put it back and it works thanks again for the help all appriciated
Re: Fan won't kick in
My pleasure 
Re: Fan won't kick in
I've discovered heating my switch with a blowtorch puts the fan on but the water in the rad doesn't when its reading nearly 110 on the gauge. Waiting for a laser thermometer from ebay coming so I can tell exactly what temp the switch works at!
Re: Fan won't kick in
Hmm - suppose the question is : -
Faulty switch, gauge temperature sender or inaccurate temperature gauge.
Father in law used to have a Corsa-B
Temperature gauge regularly got up to 103' before the fan kicked in.
I replaced the switch and sender with new items, and it made no difference at all.
Lesson learnt - the gauge was reading very high but in reality everything else was working fine.
Faulty switch, gauge temperature sender or inaccurate temperature gauge.
Father in law used to have a Corsa-B
Temperature gauge regularly got up to 103' before the fan kicked in.
I replaced the switch and sender with new items, and it made no difference at all.
Lesson learnt - the gauge was reading very high but in reality everything else was working fine.
Re: Fan won't kick in
Bought a new switch for the gauge, made no difference. Fan used to come on at 95 on the gauge without the thermostat in. Strange one
Re: Fan won't kick in
That sounds perfectly normal...sribobby wrote:Bought a new switch for the gauge, made no difference. Fan used to come on at 95 on the gauge without the thermostat in. Strange one
The only thing that you would notice is that your car would take longer to get up to 95' because the coolant is constantly being gently cooled by the air flow through the radiator.
Bear in mind that there are two temperature sensors and one switch on a cavalier.
1 - Sensor on the front top part (thermostat end) of thermostat housing for the temperature gauge.
Should be a female "Lucar" spade connector on the top of the sensor with a single blue wire slid onto it.
A faulty sensor will give inaccurate gauge readings.
2 - Sensor on rear of the thermostat housing near to the alternator - for the engine ecu.
A rectangular blue sensor with a two wire connector clipped on.
A faulty sensor will usually cause some engine starting, emissions, idling or stalling problems.
3 - Switch on the rear face of the radiator - driver's side close to the power steering pump - this controls the temperature at which the fan kicks in. (Some fan switches are two stage - so two switches in one).
A cylinder shaped sensor with either two or three wired connector clipped onto it.
A faulty switch usually results in the fan not kicking in, potentially leading to over heating and so may cause engine / cooling system damage. (Warped cylinder head / head gasket failure / cooling system boiling over etc.)
Re: Fan won't kick in
If you are being pedantic..
The thermostat could be considered to be a fluid switch.
Either open or closed.
If it fails in the open position or removed, then no damage should result.
but due to continual air cooling through the radiator it will take the engine longer to get up to temperature and so fuel consumption may increase - more so in cooler ambient weather / temperatures.
A thermostat that fails in the closed position (not very common) will prevent coolant getting to the radiator, and so over heating is very likely...the fan switch will not kick in quickly enough as the hot water is not reaching the fan switch.
The fan switch may trigger eventually due to "heat soak" through the pipework, but by the time it does, it will be far too late.
Again engine or cooling system damage could easily occur.
In instances where I have had a burst radiator (always seems to happen on a hot summers day), I have managed to limp the car home by shorting out the fan switch so that it is constantly blowing air onto the front of the engine.
The thermostat could be considered to be a fluid switch.
Either open or closed.
If it fails in the open position or removed, then no damage should result.
but due to continual air cooling through the radiator it will take the engine longer to get up to temperature and so fuel consumption may increase - more so in cooler ambient weather / temperatures.
A thermostat that fails in the closed position (not very common) will prevent coolant getting to the radiator, and so over heating is very likely...the fan switch will not kick in quickly enough as the hot water is not reaching the fan switch.
The fan switch may trigger eventually due to "heat soak" through the pipework, but by the time it does, it will be far too late.
Again engine or cooling system damage could easily occur.
In instances where I have had a burst radiator (always seems to happen on a hot summers day), I have managed to limp the car home by shorting out the fan switch so that it is constantly blowing air onto the front of the engine.
Re: Fan won't kick in
Mine is two speed, replaced resistor, fan switch, stat, gauge switch and radiator. Still goes towards 110 with no fan operating.
Re: Fan won't kick in
Stupid question -
Fuses?
Connectors corroded or burnt contacts?
Fuses?
Connectors corroded or burnt contacts?
Re: Fan won't kick in
Everything's in good shape as fan works if I bridge the pns or heat rad switch with blowtorch
Re: Fan won't kick in
It has to be a dodgy thermo-switch then.
Sadly, brand new and OEM doesn't always mean it isn't faulty.
Oil pressure senders are a prime example of that as PlanetC will tell you.
Sadly, brand new and OEM doesn't always mean it isn't faulty.
Oil pressure senders are a prime example of that as PlanetC will tell you.
Re: Fan won't kick in
The radiator may have a blockage at the bottom stopping the hot water getting to the thermo switch therefore not heating the switch to put the fan on. Flush the rad out and see if that helps.
Re: Fan won't kick in
It is worth doing a back flush of your radiator anyway as it would cost nothing to do (apart from the cost of coolant),
and is unlikely to cause any issues, unless any settled crud is also blocking a pin hole in the radiator.
It is always nice to have a fresh batch of coolant in there.
And it will tick one more item off from the suspect list.
and is unlikely to cause any issues, unless any settled crud is also blocking a pin hole in the radiator.
It is always nice to have a fresh batch of coolant in there.
And it will tick one more item off from the suspect list.
Re: Fan won't kick in
Radiators brand new so can't see it being blocked. Tried heating two different switches with blowtorch and fan comes on 100%. Surely if both switches were dodgy they wouldn't turn the fan on with torch?
Re: Fan won't kick in
Unless they are switching at too high a temperature.
If you have changed the fan sensor switch and the small temperature sensor on the thermostat housing,
that can only leave the temperature gauge itself.
It would be great if you had a temperature tester - such as used for cooking.
(Sugar or sunday roast) so that you could verify if the switch is switching wrong or the sender is sensing wrong or the gauge is reading wrong.
If you have changed the fan sensor switch and the small temperature sensor on the thermostat housing,
that can only leave the temperature gauge itself.
It would be great if you had a temperature tester - such as used for cooking.
(Sugar or sunday roast) so that you could verify if the switch is switching wrong or the sender is sensing wrong or the gauge is reading wrong.
Re: Fan won't kick in
If you have an ohm-meter, then you could test the temperature sensor and gauge as follows.
A digital meter is best for this.
Here are the values for resistance versus temperature in degrees Celsius.
As detailed in Global TIS.
These are below the scale of the temperature gauge.
Too Cold.
0'c - 5887 ohms
10'c - 3791 ohms
20'c - 2511 ohms
30'c - 1715 ohms
40'c - 1200 ohms
50'c - 851 ohms
60'c - 612 ohms
Temperature gauge should be able to display the following values.
70'c - 446 ohms (blue area - cold).
80'c - 329 ohms
90'c - 246 ohms
100'c - 186 ohms
110'c - 142 ohms (red area - too hot!!)
These are off the scale of the temperature gauge.
120'c - 110 ohms
130'c - 85 ohms
To test the sensor -
Connect red (+) probe of the Ohm-meter to tip of sensor
Connect black (com / -) probe of the ohm-meter to ground or the thermostat housing.
Read resistance on the ohm-meter.
Check this resistance to the closest in the list above.
Read the gauge...
Compare to the value calculated from the ohm-meter reading from the sender.
To test the gauge,
Disconnect the wire from the sender on the thermostat housing.
Insert a resister between the sender connector (not the sender itself) and the thermostat housing or a good grounding point.
Read off the temperature showing on the gauge.
It should give you an approximate idea of what the accuracy of the gauge is.
If anyone is good with mathematics (differentiation and integration - dy / dx ) - I think..
Then they may suss out the exact formular for the relationship between the two for any value.
A digital meter is best for this.
Here are the values for resistance versus temperature in degrees Celsius.
As detailed in Global TIS.
These are below the scale of the temperature gauge.
Too Cold.
0'c - 5887 ohms
10'c - 3791 ohms
20'c - 2511 ohms
30'c - 1715 ohms
40'c - 1200 ohms
50'c - 851 ohms
60'c - 612 ohms
Temperature gauge should be able to display the following values.
70'c - 446 ohms (blue area - cold).
80'c - 329 ohms
90'c - 246 ohms
100'c - 186 ohms
110'c - 142 ohms (red area - too hot!!)
These are off the scale of the temperature gauge.
120'c - 110 ohms
130'c - 85 ohms
To test the sensor -
Connect red (+) probe of the Ohm-meter to tip of sensor
Connect black (com / -) probe of the ohm-meter to ground or the thermostat housing.
Read resistance on the ohm-meter.
Check this resistance to the closest in the list above.
Read the gauge...
Compare to the value calculated from the ohm-meter reading from the sender.
To test the gauge,
Disconnect the wire from the sender on the thermostat housing.
Insert a resister between the sender connector (not the sender itself) and the thermostat housing or a good grounding point.
Read off the temperature showing on the gauge.
It should give you an approximate idea of what the accuracy of the gauge is.
If anyone is good with mathematics (differentiation and integration - dy / dx ) - I think..
Then they may suss out the exact formular for the relationship between the two for any value.
Re: Fan won't kick in
I bought an infra red thermometer to check what temp the switch was turning the fan on at when I heated it up. It said 30 degrees! Something not right there!
Re: Fan won't kick in
Seems like my fan problem is finally solved. Swapped my cool stat for a standard one and hey presto fan comes on at 90 degrees. Never thought a cool running stat would stop the fan kicking in.
Re: Fan won't kick in
I wasn't aware of the cool stat being fitted.
I mustn't have read the thread properly.
But don't understand how your gauge was getting to 110 degrees...
I would have thought that it would struggle to get up to normal temperature. (95 degrees).
Good to hear it's sorted though...
Got there in the end.
I mustn't have read the thread properly.
But don't understand how your gauge was getting to 110 degrees...
I would have thought that it would struggle to get up to normal temperature. (95 degrees).
Good to hear it's sorted though...
Got there in the end.
Re: Fan won't kick in
It was fine on the open road, just when sitting still the needle was obviously getting higher towards the 110 mark with no fan cutting in. All sorted now thankfully