Fans ?

wammers said:

As i said in my first post on this subject, i do not know about the wiring on the 3.9 classic. My DSE has a thermostat fitted in the top hose thru a relay to operate the aircon fans to assist the engine cooling whilst towing. Without that rig there is no connection to the engine temp, the aircon fans cannot be switched by the engine temp.

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3.9 Classic does have a thermo switch as a back up to aid cooling. With a P38 who knows what they did but I am surprised there is no system that uses the A/C condenser fans to supplement cooling if the engine temp was rising but using a separate thermo switch and relay has to be a good idea.

classic kev said:

3.9 Classic does have a thermo switch as a back up to aid cooling. With a P38 who knows what they did but I am surprised there is no system that uses the A/C condenser fans to supplement cooling if the engine temp was rising but using a separate thermo switch and relay has to be a good idea.

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There are those who have removed the viscous fan and rigged a thermostat via a relay thru the aircon fans to cool the engine. I think Datatek has done this. As i say my set up is just to aid cooling, his i believe does all the cooling.

wammers said:

There are those who have removed the viscous fan and rigged a thermostat via a relay thru the aircon fans to cool the engine. I think Datatek has done this. As i say my set up is just to aid cooling, his i believe does all the cooling.

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I have to say I removed the viscous off my 3.9 and have a pair of electric fans for main cooling hooked up to an adjustable thermo switch. Since I cleaned out the A/C Condenser and radiator they have never come on, not done any laning recently though so that might change!

Did the later P38's still have viscous? thought they went all electric.

classic kev said:

I have to say I removed the viscous off my 3.9 and have a pair of electric fans for main cooling hooked up to an adjustable thermo switch. Since I cleaned out the A/C Condenser and radiator they have never come on, not done any laning recently though so that might change!

Did the later P38's still have viscous? thought they went all electric.

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Mine is 1999 and that has viscous, so maybe later one's, i don't really know. But if you want to squeeze a few extra MPG a Kenlow is supposed to be good. May try one sometime as the vicous howls sometimes so it maybe getting ready for a new unit.

wammers said:

As i said in my first post on this subject, i do not know about the wiring on the 3.9 classic. My DSE has a thermostat fitted in the top hose thru a relay to operate the aircon fans to assist the engine cooling whilst towing. Without that rig there is no connection to the engine temp, the aircon fans cannot be switched by the engine temp.

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well you should get a proper range rover ie a classic then we wouldnt have to be so confused lol

fett said:

well you should get a proper range rover ie a classic then we wouldnt have to be so confused lol

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Must have improved them over the years. I can remember when they first came out doing about three transfer box's a week on warranty.

wammers said:

As i said in my first post on this subject, i do not know about the wiring on the 3.9 classic. My DSE has a thermostat fitted in the top hose thru a relay to operate the aircon fans to assist the engine cooling whilst towing. Without that rig there is no connection to the engine temp, the aircon fans cannot be switched by the engine temp.

Click to expand...

Not so sure about that Wammers.
As said above on the 3.9 there is a simple thermoswitch in the coolant system to bring on the fans when additional cooling is required by the engine. It doesn't make sense to remove that feature for the P38
On the P38 I'll quote from Rave ETM

Condensor Fans:
The HEVAC panel provides a signal normally at 12 volts for "off" and 0 volts for the "on" condition, which in the case of Petrol vehicles is fed into the ECM and diesel vehicles directly onto the coil of relay 18. In line is the Air-Con pressure switch 2, which turns the fans on/off.
When Relay 18 is energised, it provides connection between relays 13 and 14 (fan 1 and 2) in series or parallel with each other. This is dependant upon the state of the air-con pressur switch 1.
For the petrol option, when the signal enters the ECM, the ECM will switch the output on/off to the fusebox. The ECM will switch the output on sometimes for engine cooling reasons even though the engine has been turned off.

So on petrol models there is definitely the capacity for the fans to come on independantly of the aircon requirements. In the Circuit diagram there is an input from the engine coolant sensor into the HEVAC Ecu.

I can't make out if its the same for the diesel. The circuit diagram shows an input from the diesel ECM to the HEVAC same as the Petrol but the output does not go through the ECM. I would suspect that what this means is that the fans can only provide additional cooling while the engine is turned on in the case of the diesel model.
This might be down to the heavier starting requiremnts of the diesel.

wammers said:

Must have improved them over the years. I can remember when they first came out doing about three transfer box's a week on warranty.

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Ahh good , I know who to get to swap mine out for free when I need it then lol

SpudH said:

Not so sure about that Wammers.
As said above on the 3.9 there is a simple thermoswitch in the coolant system to bring on the fans when additional cooling is required by the engine. It doesn't make sense to remove that feature for the P38
On the P38 I'll quote from Rave ETM

Condensor Fans:
The HEVAC panel provides a signal normally at 12 volts for "off" and 0 volts for the "on" condition, which in the case of Petrol vehicles is fed into the ECM and diesel vehicles directly onto the coil of relay 18. In line is the Air-Con pressure switch 2, which turns the fans on/off.
When Relay 18 is energised, it provides connection between relays 13 and 14 (fan 1 and 2) in series or parallel with each other. This is dependant upon the state of the air-con pressur switch 1.
For the petrol option, when the signal enters the ECM, the ECM will switch the output on/off to the fusebox. The ECM will switch the output on sometimes for engine cooling reasons even though the engine has been turned off.

So on petrol models there is definitely the capacity for the fans to come on independantly of the aircon requirements. In the Circuit diagram there is an input from the engine coolant sensor into the HEVAC Ecu.

I can't make out if its the same for the diesel. The circuit diagram shows an input from the diesel ECM to the HEVAC same as the Petrol but the output does not go through the ECM. I would suspect that what this means is that the fans can only provide additional cooling while the engine is turned on in the case of the diesel model.
This might be down to the heavier starting requiremnts of the diesel.

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Yes have read RAVE and it does seem there is a provision for the fans to run at a reduced rate to assist the engine cooling (when the aircon is switched on). This is possibly to remove excess heat generated as the engine drives the compressor. However the fans will only come on at full power when the aircon needs to be cooled. It would appear from RAVE as i understand it, that with aircon switched off this function is lost.