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derbywill

Member Since: 25 Mar 2010
Location: Derbyshire
Posts: 539

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

1st Jun 2023 4:40pm

Penfold_6290

Member Since: 22 Sep 2021
Location: Dorset
Posts: 274

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

2nd Jun 2023 4:35pm

MadTom

Member Since: 10 Sep 2013
Location: Olomouc
Posts: 572

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

2nd Jun 2023 8:47pm

derbywill

Member Since: 25 Mar 2010
Location: Derbyshire
Posts: 539

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

3rd Jun 2023 3:35pm

MadTom

Member Since: 10 Sep 2013
Location: Olomouc
Posts: 572

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

3rd Jun 2023 9:55pm

kzycnn

Member Since: 24 Apr 2009
Location: Northumberland
Posts: 276

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

6th Jun 2023 2:25pm

derbywill

Member Since: 25 Mar 2010
Location: Derbyshire
Posts: 539

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

7th Jun 2023 1:54pm

tommac

Member Since: 03 Jul 2018
Location: devon
Posts: 26

Does the air con function when turned on?

17th Jun 2023 10:57am

derbywill

Member Since: 25 Mar 2010
Location: Derbyshire
Posts: 539

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

17th Jun 2023 9:00pm

tommac

Member Since: 03 Jul 2018
Location: devon
Posts: 26

Sounds like an electrical glitch Will. Best the multimeter out to test/fault find!

18th Jun 2023 8:13pm

NickMc

Member Since: 01 Oct 2014
Location: Norn Iron
Posts: 1568

Check the clutch on the compressor you can cheat it on with a screw driver if you’re careful.

18th Jun 2023 8:52pm

derbywill

Member Since: 25 Mar 2010
Location: Derbyshire
Posts: 539

Yep, went for the easy option first and it didn’t work

2005 90 XS
1954 86'' Series 1 tilt

18th Jun 2023 9:13pm

NickMc

Member Since: 01 Oct 2014
Location: Norn Iron
Posts: 1568

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

18th Jun 2023 9:28pm

tommac

Member Since: 03 Jul 2018
Location: devon
Posts: 26

I’d start with the relay Will- pull it, test the voltages and clean everything up.

18th Jun 2023 9:50pm

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