Heater fan on full only

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Mogman

Member
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64
Location
Scotland
Hi folks,

Our 2004 Td5 Disco with Air Con has just started blowing full-on only on the heating fan. No lower fan speed level can be set even with the manual heater button. I've heard talk of a resistor failure. Can anyone tell me what the cause might be?
 
There is a resistor that reducers the fan speed in steps so yours has failed and the default speed is max. You will have to look in your manual for the location, but on the later D1 it's on the side of the heater box and easy to change.
 
Mogman said:
Hi folks,

Our 2004 Td5 Disco with Air Con has just started blowing full-on only on the heating fan. No lower fan speed level can be set even with the manual heater button. I've heard talk of a resistor failure. Can anyone tell me what the cause might be?
Click to expand...

It's not a resistor it's a resistor pack including three resistors...just forget about it...it's only for non A/C vehicles.....on aircon'ed vehicles the blower speed is controlled by the A/C ECU through a power transistor or a power relay.........for maximum speed of the blower this transistor is bypassed by the power relay giving direct earth to the blower motor..........just if the transistor is short circuited then the blower goes mad.

To see locations open RAVE > electrical library>connector views and see C0858(power transistor) and C0901(power relay-dont confuse this one with the blower relay which is near him)............then unplug the transistor.......if the blower stops that means he's the trouble and need to be replaced.....if the blower doesnt stop even with the transistor out it means that u have to check the power relay...but even this one is controlled by the A/C ECU.

About the reason....i dunno.....it just happens:rolleyes:
 
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Thanks guys, I do have the aircon.

Sierrafery said "open RAVE >electrical library>connector views and see C0858(power transistor) and C0901(power relay", sorry but I don't know what RAVE is, is it a website or a manual I should have?
 
Mogman said:
Thanks guys, I do have the aircon.

Sierrafery said "open RAVE >electrical library>connector views and see C0858(power transistor) and C0901(power relay", sorry but I don't know what RAVE is, is it a website or a manual I should have?
Click to expand...

Download the 3'rd one The Green Oval - Downloads | Land Rover Data

untill then
powerrl.png
powertr.png
 
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Thanks for the inputs guys. Got it all working again today. On late 2003 and 2004 Td5 Discos the air-con front cabin heater fan is controlled by an electronic circuit in a case attached to a large metal heat-sink located behind the glove-box. No big resistors, it's a big MOSFET (Field Efect Transistor) used as a variable resistor. In case anyone needs the part. For Air-Con Td5 Discos up to 2003 this part is a JGN100010 but for the later vehicles it's a JGN100011. Not cheap and only Land Rover or breakers seem to have them. Now to see if I can repair the old one by replacing the MOSFET. Thanks again guys.
 
Thanks to all, and Mogman, for the part number. It was exactly what I was looking for. Discovery II 2004, with digital AC. JGN100011. I had my doubts when I ordered the part, and had to pay up a steep price. But what a relief, when the fan is running normally again.
 
Hi Mogman, you seem to be the expert on landy aircon!

i too only have a fan that operates at max speed or not at all

i've been following this thread and i took action last night. Using the rave manuals i removed the trim and glove box and got access to my blower. After a lot of struggling, i managed to remove the power transistor / heat sink component (getting access to the one of the screws was a nightmare). Just to confirm, the blower should still be operating only at max speed?

i ask because i am looking at either buying a new component or a complete blower off ebay and nabbing the part i want (although from above this unit will have to be from an 03 / 04 disco?). Just wanted to be sure this power transistor is the solution to my problems!?

thx again,

James
 
Hi James,

The symptoms on mine were that the fan would only stop or blow at full speed. After I plugged in the replacement unit it worked fine and has ever since. The screws were not the easiest to get in and out, I bought a cheap set of very long screwdrivers, 12inch long blades, from a low-cost tool shop that had magnetic tips and with care putting the unit back was much easier. The log screw drivers have been godsends on other jobs ever since.

The 03/04 part is diferent to the earlier one but a local Landy independant repair man tells me they are interchangeable, I cannot verify that as an official Landy dealer said they are not. I went for a new unit as I couldn't find a used one of the newer type but that was two years ago so there may be more around now.

Good luck.

Lawrence
 
Hi Sierrafery,

I agree but the flatpack MOSFET in the later unit that is in my Disco wasn't available when I looked two years ago, I still have the failed unit with the intention of making a spare when I find the part to fit. I think that the transistor you show is for the unit up until mid-2003 models, it wouldn't fit into mine. The two units have different part numbers and a main dealer told me they couldn't be interchanged because the ECU was modified for the later one; I can't say what the reality is so rather than risk my ECU on one of the older units I could get second hand I forked out for the direct replacement.
 
then see what's stamped on the new unit's transistor....imo it will be something similar and then find one exactly the same... though i have serious doubts about the dealer's statement... it's just about a superceded part number imho...worth a check
 
I agree with you about the likelihood it's just a superceded part number. The part number on my unit is "2SK2313". Two years ago I could only buy them by the thousand from a place in Japan, it's a Toshiba MOSFET. I just looked on ebay and now they are available for next to nothing so I'll be fixing the failed unit very soon. The in-circuit soldered in fuse also failed on mine but they are easy to find.
Cheers.
 
we have (had) the same problem. when in manual mode the fan speed button does nothing other than light an additional black bar on the ECU until max is reached and then the blower fires up.

having removed the power transistor, the unit still acts as above. this is what i understood (and wanted) to happen. ie the power transistor is not used on max blower?

the challenge now is to replace the power transistor at a reasonable price. the prices on ebay from america are crazy! $100 + Blower units on ebay are £40.

to replace the mosfet, i will need soldering irons etc? i ask because my tools in london are very limited and id rather not buy them.

thx everyone for replying so quickly!
 
yes, on max. speed blower the transiztor is bypassed... it works for the intermediate speeds... now how do you replace it is your choice, it's easy to replace just the transistor but you need to solder the wires to it's legs.
 
Hi Guys,

I've attached a not so good picture off my scanner of my failed unit. It shows the heatsink with the flat-black MOSFET that is held down by a screw and the normally attached circuit board beside it. The component sticking out from the circuit board is a thermal fuse that was held beneath the black clamp you can see held down by the same screw as the MOSFET. This fuse had also blown in mine.

I see equivalents of this MOSFET (K2313, also 2sK2313) on ebay in the UK for as little as £1.60, they are shipped from Hong Kong.

Soldering and the use of thermal compound is a must.
 

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i opened up the unit last night and i wished i taken some photos. just removing the circuit board requires a soldering iron. what are you saying; that the mosfet is underneath the circuit board screwed to the heatsink?

im going to be a real mug to purchase a new unit aren't i? i'd rather spend the money on a tank of gas!

another question i have; the condensor fan situated behind the front grill - what does it do? I ask because mine has seized and therefore is disconnected. the car has been serviced by land specialists and they just said it needs replacing - but not that it was critical.

when reading the rave manual air con section it talks about how the system uses vehicle speed to determine how much fan speed is needed. is this something to do with that?
 
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