2002 TD5 auto - aircon fan

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thebiglad

thebiglad

Well-Known Member
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Central France
Hi all, have a query on my car. The aircon fan in front of the radiator stays on all the time the engine is running and it shouldn't and I don't want to wear it out prematurely.

I've tried:

1. Replacing the Engine Coolant Temp sensor - no change;

2. Interrogated the engine ECU for overheats, none recorded, cleared faults;

3. Checked the coolant for level and airlocks - none found;

4. Pulled the yellow relay (2nd from rearmost one)in the engine bay fusebox - this kills the fan. Swapped for another relay and the fan keeps running, so unlikely to be a faulty relay. Does anyone know what else this relay operates?

I have a Hawkeye on order which should arrive soon, but tbh I'm getting cheesed off with this thing whirring away all the time.

Anyone got any suggestions?

Cheers
Dave
 
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Ok so just to update this, I've just been out and run through the Climate Control manual diagnostic and no faults were found.
 
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Electrics/electronics is my field so i could lead u step by step on this.....I have just 2 questions:
1. Are u speaking about the thing they named "blower" in RAVE?
2. Can u rob along together easy with electric diagrams?
 
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First step.......take out the blower switch and see if posotion 0ff or 4 arent on short circuit......pull out one by one the wires which are coresponding to these positions(if u can)...if not u'll have to check the feeds at the relay's pins...at off position of the switch it must not have feed at one of the pins....have to chek the diagram..... the logic of this steps stays here:

Blower speed
The blower can be selected off or to run at one of four speeds. While the ignition is on, when the blower switch is set to positions 1, 2, 3, or 4, ignition power energises the blower relay, which supplies battery power to the blower. At switch positions 1, 2 and 3, the blower switch also connects the blower to different earth paths through the resistor pack, to produce corresponding differences of blower operating voltage and speed. At position 4, the blower switch connects an earth direct to the blower, bypassing the resistor pack, and full battery voltage drives the blower at maximum speed.

Now according to what speed has the blower that contact of the switch could be blocked on closed position and feeding the relay.

If everything is OK with the switch then it could be a wireing thing and that will be a bit more complicated but we'll go thro the scheme and find it............it also could be the resistor pack, its a seald unit behind the glove box and could make tricks........that's why is interchangeable looks like this http://www.partsgeek.com/catalog/20...ry/climate_control/blower_motor_resistor.html
U'll need a check lamp or a multimeter and a soldering gun.
 
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i checked the diagram...........at the blower relay(R176) when blower switch is on position 0 check between pin 1 and 2 (C0153).....u must not have power..........but as u described i think u'll have.....it means it gets feed(though it shouldnt) from the switch.....

If u open RAVE >electric circuits diagram>heater blower u'll see the logic(the right upper side of the diagram).....if the relay isnt feeded it means that its on open position and the blower motor can get feed just via resistor pack(if it has a short circuit in it) .....simple ast that:)

First step to b sure it isnt the resistor pack is to unplug it(with the switch off) .....if the blower doesnt stop he's OK.
 
I think we are slightly at cross purposes:)

The fan I'm talking about is the one in front of the aircon condensor radiator just behind the radiator grill - not the one in the in-car heating system.

The "Engine cooling fan control" is discussed on page 82-20 of RAVE Disco II. This electric fan works in conjunction with the aircon system, but also works as back-up engine cooling. On my car however it is running all the time.

Some people will say that this can be caused by a previous engine overheat situation, so the ECU calls up the electric fan to aid the viscous fan. However, when I had the car remapped recently we checked all fault codes and cancelled them and none were overheat related.

Incidently the car has always had this issue, not just since the remap.

Cheers for the replies though

Dave
 
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Ok I found it.... as they said the main relay feeds the coil of the cooling fan relay.........if i can find the diagram and if it's an electric issue we'll sort it out........my concern is with the ECM's involvement
 
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I've had a local garage on the phone just this morning with exactly the same problem.Seen it before but ages ago,from memory the HEVAC panel provides an earth path through the engine ecu to pull in the relay.Its not clever enough to log a fault for this problem,so nothing will log.
Unfortunately the best way to prove it is to sub over a panel from a "Known good car" (As LR dealer tech support are so fond of saying....)
 
sierrafery said:
Ok I found it....u said u checked the relay, was it the main relay or the cooling fan relay? as they said the main relay feeds the coil of the cooling fan relay.........if i can find the diagram and if it's an electric issue we'll sort it out........my concern is with the ECM's involvement
Click to expand...


Hi SF, the relay I have 'played with' is in the engine bay fusebox, it's a yellow one, second from the left in the attached pic.

I don't know whether that is the main relay or the cooling relay?


Dave
 

Attachments

  • TD5 engine bay fusebox (960 x 540).jpg
    TD5 engine bay fusebox (960 x 540).jpg
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If u can locate pin C0658-4 at the ECM and check if it has earth on it when the fan shouldnt work..... and it hasnt then its an electrical(short circuit) issue....it means that the cooling fan relay gets earth from somewhere else. If the ECM sends the earth when the engine is cool then is beyond my knowledge.......though it has an interface with the A/C ECU either

if u go to electrical lybrary>connetor views>0658 u'll find it
 
Also the A/C ECU has the pin C0793-9 named "cooling fan request" :
Engine cooling fan control
While the A/C system is on, operation of the electric engine cooling fan, to assist refrigerant condenser operation, is determined by a combination of vehicle speed and external air temperature. When cooling fan operation is required, the ATC ECU outputs a cooling fan request to the ECM, which then energises the cooling fan relay. The cooling fan request is output if vehicle speed is 80 km/h or less while the external air temperature is 28 °C (82 °F) or more. The
request is cancelled, and the cooling fan switched off, if either the vehicle speed increases to 100 km/h, or the external air temperature decreases to 25 °C (77 °F).

Think about the underlined part too..........to be certain u can pull out connector C0793 from the AC ECU and if the cooling fan stops it means that there is the problem
 
What your posting refers to the Air conditioning operation............

The ENGINE ECU can also request the cooling fan as well, this is where the "latch" comes from. It needs to be "hooked" up to reset it.
 
Urban Panzer said:
What your posting refers to the Air conditioning operation............

The ENGINE ECU can also request the cooling fan as well, this is where the "latch" comes from. It needs to be "hooked" up to reset it.
Click to expand...



Yes Nick, hopefuly tuesday when The Hawkeye arrives - and no, it's not a blôody hairy indian.

:D:D:D:D:D:D:D:D:D
 
jonathanp said:
Is there a temp sensor on the auto box or auto box oil pipe to oil cooler that is designed to switch on the fan as an extra cooler if the ATF gets too hot ?? Regards Jonathan
Click to expand...

Hi Jonathan and thanks for your reply.

The autobox does have a temp sensor on it's oil cooler but as far as I can see it has no connection with this current problem, it just illuminates a dashboard warning light.

Thank you though,

Dave
 
Hi,

Sorry am totally new to all this. Been searching the forum and found this post.

I have exactly the same issue as described here with my AirCon Fan being on all the time.
I have a 51 plate Disco TD5.
TheBigLad - were you able to solve the problem on yours?
Can anyone else offer any advice at all please as I don't fancy the dealer prices :confused:

Many Thanks

Dipsterson
 
First of all I must apologise to all the other contributors on this thread.

I did get my Hawkeye and with it was able to resolve the "aircon fan running permanently" problem.

I just went into the main engine ECU menu and on there was a setting for "forced assist - yes or no". I selected No and the fan stopped it's permanent running.

Apologies again, too much on my plate I suppose.

Cheers
Dave
 
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