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derbywill



Member Since: 25 Mar 2010
Location: Derbyshire
Posts: 559
England 2005 Defender 90 Td5 XS CSW Java Black
Air Con fan running majority of the time
Bit of a strange one on my 2005 Td5 90 with Air Con, the electric fan runs quite often even with the aircon off.
I've researched abit and found if it overheated the electric fan would kick in, and only stop when the fault memory is cleared even if there isn't a fault in the memory.
But mine isn't like that, I can clear the memory and even when cold the fan will kick in again.
In the parameters it is saying fan requested. So I'm guessing it is getting a signal from the AC even tho its switch off. There is a control type box behind the rotary switches, anybody had an issue with this or a similar issue?

Cheers

Will 2005 90 XS
1954 86'' Series 1 tilt
1968 88” 2A 200tdi
2002 110 Hardtop
Post #994740 1st Jun 2023 3:40pm
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Penfold_6290



Member Since: 22 Sep 2021
Location: Dorset
Posts: 320
United Kingdom 2002 Defender 110 Td5 CSW Epsom Green
That's an odd one. The cooling fan on the condenser is controlled by the ECU. Extract from the Td5 electrical library below. So for some reason your ECU thinks it needs to run the fan, I would check the relays and connectors to make sure there is no earth path being provided inadvertently but also maybe check the temperature sender on the engine as that might be giving a false reading leading to the ECU thinking the engine is getting hot.

Temp spikes on the temp guage are sometimes a symptom of poor earthing of the ECU itself. If you haven't already done so I'd recommend you attach an earth wire to the ECU shell and take it to the earth connector on the gearbox or straight to the battery.



Click image to enlarge
Post #994867 2nd Jun 2023 3:35pm
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MadTom



Member Since: 10 Sep 2013
Location: Olomouc
Posts: 625
Czech Republic 1999 Defender 130 Td5 HCPU Baltic Blue
There is "ECU" inside the AC unit. First try to unplug whole AC. "Drobek" = The Small One - Discovery 2, "Blufínek" = The Blue Thing - Defender 130, and for me at least Ford Mondeo Smile
Post #994903 2nd Jun 2023 7:47pm
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derbywill



Member Since: 25 Mar 2010
Location: Derbyshire
Posts: 559
England 2005 Defender 90 Td5 XS CSW Java Black
Thanks guys, I'll have a look next week, its an odd one, if I put the air con and turn it off again it stops it.
Strange!
Cheers

Will 2005 90 XS
1954 86'' Series 1 tilt
1968 88” 2A 200tdi
2002 110 Hardtop
Post #994967 3rd Jun 2023 2:35pm
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MadTom



Member Since: 10 Sep 2013
Location: Olomouc
Posts: 625
Czech Republic 1999 Defender 130 Td5 HCPU Baltic Blue
AC fan (the electric one behind front mask) is powered over a relay controlled from engine ECU. AC ECU is "asking" for this fan over one wire to engine ECU. Disconnecting the AC ECU should stop the fan. "Drobek" = The Small One - Discovery 2, "Blufínek" = The Blue Thing - Defender 130, and for me at least Ford Mondeo Smile
Post #995004 3rd Jun 2023 8:55pm
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kzycnn



Member Since: 24 Apr 2009
Location: Northumberland
Posts: 277
United Kingdom 2003 Defender 110 Td5 XS CSW Oslo Blue
I had exactly the same problem some years ago. Followed the same logic but got nowhere. Finally had an aircon recharge and that sorted it - been fine since.

Tony
Post #995331 6th Jun 2023 1:25pm
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derbywill



Member Since: 25 Mar 2010
Location: Derbyshire
Posts: 559
England 2005 Defender 90 Td5 XS CSW Java Black
That is interesting Tony, It hasn't been re gassed in about 5 years when I fitted a new condenser.

Cheers

Will 2005 90 XS
1954 86'' Series 1 tilt
1968 88” 2A 200tdi
2002 110 Hardtop
Post #995434 7th Jun 2023 12:54pm
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tommac



Member Since: 03 Jul 2018
Location: devon
Posts: 26
United Kingdom 2001 Defender 110 Td5 DCPU Alveston Red
Does the air con function when turned on?
Post #996594 17th Jun 2023 9:57am
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derbywill



Member Since: 25 Mar 2010
Location: Derbyshire
Posts: 559
England 2005 Defender 90 Td5 XS CSW Java Black
Yes air con is working fine, I’ve had the pressures checked and it was 150g down, now topped up to spec and still doing it.
I had it idling earlier for a few minutes with the air con off and the fan kept cutting in and turning off, definitely an electrical fault somewhere.

Cheers

Will 2005 90 XS
1954 86'' Series 1 tilt
1968 88” 2A 200tdi
2002 110 Hardtop
Post #996662 17th Jun 2023 8:00pm
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tommac



Member Since: 03 Jul 2018
Location: devon
Posts: 26
United Kingdom 2001 Defender 110 Td5 DCPU Alveston Red
Sounds like an electrical glitch Will. Best the multimeter out to test/fault find!
Post #996780 18th Jun 2023 7:13pm
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NickMc



Member Since: 01 Oct 2014
Location: Norn Iron
Posts: 1628
Northern Ireland 2006 Defender 90 Td5 HT Bonatti Grey
Check the clutch on the compressor you can cheat it on with a screw driver if you’re careful.
Post #996784 18th Jun 2023 7:52pm
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derbywill



Member Since: 25 Mar 2010
Location: Derbyshire
Posts: 559
England 2005 Defender 90 Td5 XS CSW Java Black
Yep, went for the easy option first and it didn’t work Laughing 2005 90 XS
1954 86'' Series 1 tilt
1968 88” 2A 200tdi
2002 110 Hardtop
Post #996787 18th Jun 2023 8:13pm
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NickMc



Member Since: 01 Oct 2014
Location: Norn Iron
Posts: 1628
Northern Ireland 2006 Defender 90 Td5 HT Bonatti Grey
Some of the wiring is the brown plug attached to the backside of the fuse box under the middle of the dash on the LHS looking at it. Can’t remember much else as don’t see many with it here, or anyone that wanted to pay to fix it Rolling Eyes
Post #996791 18th Jun 2023 8:28pm
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tommac



Member Since: 03 Jul 2018
Location: devon
Posts: 26
United Kingdom 2001 Defender 110 Td5 DCPU Alveston Red
I’d start with the relay Will- pull it, test the voltages and clean everything up.
Post #996794 18th Jun 2023 8:50pm
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derbywill



Member Since: 25 Mar 2010
Location: Derbyshire
Posts: 559
England 2005 Defender 90 Td5 XS CSW Java Black
Finally had time to look at this issue, so time for an update.

Got the old test light out and multi meter checking voltages, relay and fuse connections and all was ok.
So looking at the wiring diagram there is a control box that sits behind the A/C switches, I tried moving the loom to this and the fan started turning off and on. So I disconnected the control box, cleaned the terminals and tightened them up and it still faltered.
So I removed the control box, removed the casing and resoldered the joints inside and hey presto it's been a week and it has solved the issue!

Hope this helps others with a similar issue.

Cheers

Will 2005 90 XS
1954 86'' Series 1 tilt
1968 88” 2A 200tdi
2002 110 Hardtop
Post #1033387 30th Apr 2024 12:02pm
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