 | Home > Technical > AC Aircon trouble shooting. When should cooling fan start? |
 
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| UtilityTruck Member Since: 09 Jan 2014 Location: Oxford Posts: 463  
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2.2 2014 110”
Some time back the A/C effectiveness seemed to drop off- it still works and blows cold air, but it struggles to keep up when it’s really hot and it used to be a lot better. Prompted by this thread; https://www.defender2.net/forum/topic72615.html I realised I could not remember the last time my cooling fan for the AC had kicked in. Following the diagram in this thread; https://www.defender2.net/forum/post385404.html I’ve checked fuse F6(20A) and F14(5A) in the battery junction box that are related to the AC (I think F6 is for the fan). Both OK. Fuses in the dash fuse board are also OK. When AC is turned on, Relay R181 for the compressor clutch clicks and I can feel the pipe on the compressor getting cold. Relay R117 for the fan never clicks and the pins on the fan connector at the condenser always read 0V. So I swapped the relay out for a known good one, no change. So my question is, when should the fan for AC be on??? Some have said in the other thread it comes on with AC, some that the ambient temp has to be higher.. does anyone know the actual logic employed? It’s about 22degs here today. [/i] 2014 Keswick Utility 2.2 |
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29th May 2020 1:42pm |
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| LandRoverAnorak Member Since: 17 Jul 2011 Location: Surrey Posts: 11324
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The detailed answer is within Widgets' post in the first thread that you've listed, which can basically be summarised as 'it depends...'. It's also worth noting that it may not actually be obvious when the A/C fan is running as the fan noise that people reported was almost certainly the viscous engine cooling fan.
Your not-cold A/C is most likely a sign that it needs to be re-gassed. Darren 110 USW BUILD THREAD - EXPEDITION TRAILER - 200tdi 90 BUILD THREAD - SANKEY TRAILER - IG@landroveranorak "You came in that thing? You're braver than I thought!" - Princess Leia |
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29th May 2020 2:15pm |
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| Martin Site Admin Member Since: 02 Apr 2007 Location: Hook Norton Posts: 6605 
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The condenser fan relay is controlled by the ECU and isn't simply on when the AC button is pressed.
To be honest, it hardly runs in my experience, perhaps at high engine temperatures/load.  1988 90 Td5 NAS soft top
2015 D90 XS SW |
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29th May 2020 2:22pm |
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| UtilityTruck Member Since: 09 Jan 2014 Location: Oxford Posts: 463
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Thanks, I’ll look at a re-gas! 2014 Keswick Utility 2.2
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29th May 2020 2:32pm |
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| Bluest Member Since: 23 Apr 2016 Location: Lancashire Posts: 4210 
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I recall someone telling me it doesn't run is there is insufficient gas pressure in the system as well. So lack of fan could a sign of needing a recharge.
Contrary to others, my fan does run a lot, even in relatively cool (not cold) conditions. It's quite easy to hear it kicking in and out from outside the vehicle and is distinct from the engine cooling fan noise. 2007 110 TDCi Station Wagon XS |
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29th May 2020 3:41pm |
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| Martin Site Admin Member Since: 02 Apr 2007 Location: Hook Norton Posts: 6605
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The compressor won’t kick in if there’s not enough gas pressure.
1988 90 Td5 NAS soft top
2015 D90 XS SW |
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29th May 2020 9:32pm |
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| bluebottle Member Since: 08 May 2015 Location: Not in my Landy enough! Posts: 705
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It also shuts off if someone has overfilled the system... ask how I know
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31st May 2020 7:21am |
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