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Electric fan. Thermo fan. A/C condenser fan. 07 Navara D40
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Old 11-01-2018, 05:46 AM
Kelzhere Kelzhere is offline
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Default Electric fan. Thermo fan. A/C condenser fan. 07 Navara D40

Hi there. Question i cant find an answer for - (Nissan navara d40 st-x 2007 yd25 spain built. Diesel. manual.) The secondary fan attached to the radiator behind the clutch fan... heard it called by these names- the thermo fan/ electric fan / A/C condenser fan...
Its not engaging or working at all. Done a starter test (where u turn ignition on/off pump pedal so many times etc) it did turn on and run the low and high speeds. So i am wondering where the fault may be. I was told to replace the entire fan, yet i was wondering what actually causes it to engage. A pressure or temp sensor? I read they are to kick in when air conditioning is running or above a certain temp. Which it doesnt.I was told there is a resistor on the electric fan that must be faulty. Does anyone know? Or Could this b a relay problem? Dont want to replace the fan and find its a fault elsewhere.
Its stinking hot in Australia thru summer and feel its neccessary to have this fan functioning like it should.
The plastic bleeder join along the heater hose blew and lost water. Noticed as passenger the aircon not working, leant over to see gauge on high/ engine overheating.
Head warped, had it shaved back and replaced. Thermostat replaced. Chemically flushed out the radiator and Bled the air out of the cooling system as gud as cud be.
Still over heating under any work like going up any incline especially if aircon is on. Ordered a new radiator as we used stopleak in it after the overheating and before head was tested and shaved back. It sat for awhile during the head repairs so it definitely prob blocked up some. Also ordering a new clutch fan. Hopefully the new radiator and clutch fan coming will resolve the overheating but just lost with this little fan and it not engaging which may have been the initial source to all the problems if not just the blown plastic bleeder part.
Doesnt seem to b a lot of info on this. Read the manual part but electrical stuff is over my head... brrt.
Please help or inform me before i order a new thermo fan.
Thanks. Kelly.
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  #2  
Old 11-01-2018, 06:19 AM
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Can't really help with the settings of when it should cut in, but if the fan is working when performing diagnostics on it, it would appear the fan is OK. I'm sure someone with a d40 who knows under what conditions it should engage will reply shortly.
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Old 11-01-2018, 06:45 AM
Kelzhere Kelzhere is offline
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Thanks for the reply anyways bods. Yeah i read a few differing notes on when it should engage. It be nice to know for sure but regardless it still doesnt kick at all -even when overheating.. so im thinking whatever triggers it to engage is faulty but i dont know what that is. I agree- It wud seem the fan is ok. I told a specialist that it kicks in under diagnostic tests. he said a resistor problem and to replace the whole fan. I see what may look like a resistor built into the housing? He didnt want to talk about trying to fix or replace that smaller part. So im still lost on the whole matter

Last edited by Kelzhere; 11-01-2018 at 06:51 AM.
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Old 11-01-2018, 07:21 AM
jonney jonney is offline
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the fan should come on when the engine reaches a certain temp or when the aircon is turned on. check the temp sensor that opperates this fan.
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Old 11-01-2018, 07:22 AM
Kelzhere Kelzhere is offline
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Quote:
Originally Posted by jonney View Post
the fan should come on when the engine reaches a certain temp or when the aircon is turned on. check the temp sensor that opperates this fan.
Thanks Jonney. Where can i find the temp sensor and how do i check it?
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Old 11-01-2018, 09:28 AM
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Old.Tony Old.Tony is offline
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There are two main reasons why the fan will engage without entering diagnostic mode.

1) The air conditioner is on

2) The coolant temperature has reached or exceeded 105C

Obviously a piece of cake to test - turn on the aircon! Set the fan speed to 1, 2, 3 or 4 and turn the dial to 'Max Aircon'.

Getting the coolant to 105C actually requires considerable effort, like towing something heavy up a steep hill.

If the fan isn't coming on with the air conditioner then there may be something not quite right with the air conditioning compressor.
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Old 11-01-2018, 01:59 PM
Kelzhere Kelzhere is offline
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Quote:
Originally Posted by Old.Tony View Post
There are two main reasons why the fan will engage without entering diagnostic mode.

1) The air conditioner is on

2) The coolant temperature has reached or exceeded 105C

Obviously a piece of cake to test - turn on the aircon! Set the fan speed to 1, 2, 3 or 4 and turn the dial to 'Max Aircon'.

Getting the coolant to 105C actually requires considerable effort, like towing something heavy up a steep hill.

If the fan isn't coming on with the air conditioner then there may be something not quite right with the air conditioning compressor.

Thanks Young.Tony. 😁
i mentioned in the comments that It doesnt come on at all even when car was overheating which wud have to be well over 105C .nor turning on with the aircon, so im curious to whether theres a faulty sensor or could this be a relay problem?. (I know nothing about relays or electrical stuff. Fuses are as tricky as i get.)
Curious to why u think it could be the compressor... the airconditioning itself doesnt seem to b missing a beat.
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Old 11-01-2018, 08:52 PM
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The only way to know if the sensor knows that the car is overheating is to read the information from the ECU. Thankfully, in the D40, this is easy.

You can buy Bluetooth OBD adapters (must be ELM327) on eBay for as little as a few dollars. Grab one, connect it to your OBD port (under the dash in front of the driver's left knee) and grab an Android phone, go into bluetooth and pair with this adapter.

Hop into the Play Store and search for the app 'Torque'. Install, open, then create a vehicle profile providing roughly the correct information but ensure the fuel type is correct (that's really the only issue you need to fix). Into 'Realtime' you'll find a default set of gauges, if 'Coolant' is not one, swipe the screen one way or the other until you either find a 'Coolant' display or a blank area. Long-tap the screen, choose 'Add Display', choose the display type you want, then scroll to 'Engine Coolant Temperature'. Select the size (recommend 'Small' or 'Medium') and it should then display the ECU's data for this sensor.

You can now monitor the coolant temperature. Really, I don't let my car get to 105C. I have an alarm set at 104C and I'm usually watching the temperature as intently as driving allows, backing off (using gears, even though mine's an auto) as the temperature approaches 100C. I don't want to be stuck hundreds of km from home with a blown head gasket!

So if the fan doesn't come on with the aircon, I'd be interested to find out if your compressor is working properly AND if the wires are all attached correctly to the compressor. We had one user here who'd had some work done on his car by a mechanic who'd accidentally disconnected one of the wires from the compressor and all sorts of strange things started happening. Although the car's service manual doesn't state it, it does appear that the air conditioning compressor has a considerably more important role in the ECU's program than we thought, which is why it needs to be checked. Look for loose wires around it, remove any easily-unplugged wires and clean the contacts, and try the test again.

In short, if the diagnostics mode of the ECU causes the thermal fan to start, then the ECU is capable of controlling the fan properly and the fault (in not bringing on the fan) will be either in coolant temperature measurement (hence the OBD tool described above) or in the aircon compressor's electrical connections. There are no other sensors that decide when to bring that electric fan on - in fact, the fan is only present on models with air conditioning fitted.

The precise (from the manual) conditions where the electric cooling fan are operated are dependant on:

a) vehicle speed sensor (which is the ABS system in our cars)
b) engine coolant temperature
c) air conditioner switch
d) air conditioning refrigerant pressure

The precise set of conditions (again, in the manual) under which the fan will be activated are:

1) Air con switch is 'on' with the fan at speeds 1 through 4 AND refrigerant pressure is > 1580kPa
2) Engine coolant is between 98C and 105C AND vehicle speed is under 40km/h (fan speed = low)
3) Engine coolant is over 105C and vehicle is travelling at any speed (fan speed = high)

Hope that helps!
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Old 12-01-2018, 02:53 AM
Kelzhere Kelzhere is offline
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Quote:
Originally Posted by Old.Tony View Post
The only way to know if the sensor knows that the car is overheating is to read the information from the ECU. Thankfully, in the D40, this is easy.

You can buy Bluetooth OBD adapters (must be ELM327) on eBay for as little as a few dollars. Grab one, connect it to your OBD port (under the dash in front of the driver's left knee) and grab an Android phone, go into bluetooth and pair with this adapter.

Hop into the Play Store and search for the app 'Torque'. Install, open, then create a vehicle profile providing roughly the correct information but ensure the fuel type is correct (that's really the only issue you need to fix). Into 'Realtime' you'll find a default set of gauges, if 'Coolant' is not one, swipe the screen one way or the other until you either find a 'Coolant' display or a blank area. Long-tap the screen, choose 'Add Display', choose the display type you want, then scroll to 'Engine Coolant Temperature'. Select the size (recommend 'Small' or 'Medium') and it should then display the ECU's data for this sensor.

You can now monitor the coolant temperature. Really, I don't let my car get to 105C. I have an alarm set at 104C and I'm usually watching the temperature as intently as driving allows, backing off (using gears, even though mine's an auto) as the temperature approaches 100C. I don't want to be stuck hundreds of km from home with a blown head gasket!

So if the fan doesn't come on with the aircon, I'd be interested to find out if your compressor is working properly AND if the wires are all attached correctly to the compressor. We had one user here who'd had some work done on his car by a mechanic who'd accidentally disconnected one of the wires from the compressor and all sorts of strange things started happening. Although the car's service manual doesn't state it, it does appear that the air conditioning compressor has a considerably more important role in the ECU's program than we thought, which is why it needs to be checked. Look for loose wires around it, remove any easily-unplugged wires and clean the contacts, and try the test again.

In short, if the diagnostics mode of the ECU causes the thermal fan to start, then the ECU is capable of controlling the fan properly and the fault (in not bringing on the fan) will be either in coolant temperature measurement (hence the OBD tool described above) or in the aircon compressor's electrical connections. There are no other sensors that decide when to bring that electric fan on - in fact, the fan is only present on models with air conditioning fitted.

The precise (from the manual) conditions where the electric cooling fan are operated are dependant on:

a) vehicle speed sensor (which is the ABS system in our cars)
b) engine coolant temperature
c) air conditioner switch
d) air conditioning refrigerant pressure

The precise set of conditions (again, in the manual) under which the fan will be activated are:

1) Air con switch is 'on' with the fan at speeds 1 through 4 AND refrigerant pressure is > 1580kPa
2) Engine coolant is between 98C and 105C AND vehicle speed is under 40km/h (fan speed = low)
3) Engine coolant is over 105C and vehicle is travelling at any speed (fan speed = high)

Hope that helps!
Wow. Thats extremely informative and helpful. Thankyou for taking time to explain all that in an easy to understand way. Im going to go have a look now at the connections/wiring around the compressor.
So The OBD tool will give me the temp measurements and how do i diagnose whether it is a coolant temp measurement problem?
Thanks Tony.
The alarm is good idea. I think i scanned across a post on here about that a few days ago. Might look into it.

Last edited by Kelzhere; 12-01-2018 at 02:55 AM.
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  #10  
Old 12-01-2018, 09:58 AM
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Testing whether or not your ECU is getting the correct information from the temperature sensor can be done in two ways.

1) Grab a thermometer. Personally I'd use a non-contact one and aim it at the radiator wall right next to the sensor. It won't be precise - it will be a couple of degrees lower - but it will be close.

2) Know the car. Glow plugs turn off at 85C. Normal idle temp is 91C. Normal unladen driving temp is around 93-96C. If these figures are familiar then your sensor is reading correctly.
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a/c condenser, d40, electric fan, nissan navara, thermo fan

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