csimoes Posted August 11, 2013 Share Posted August 11, 2013 hi as my first post just want to say this is a great forum i'm writing from Portugal so be pacient with my english. after some PM with Nigel i'm thinking on going MS on my RR 3.9 EFI Decat. the only thing that is i'm not shure about is if the AC can work ok without de Lucas ECU. from what i read in RAVE, it controles some parts of the AC. i can be wrong so i need your help. overhere we have a lot of offroading on sand and the engine gets very hot and when the viscous fan can do the job the electric fan from the AC come on. will this still work/be controlled by MS? will the AC work only with MS? maybie this are stupid douts by... a like my AC as we have 3 or 4 months of the year with 30º plus cheers Carlos Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted August 12, 2013 Share Posted August 12, 2013 The AC gives the Lucas ECU a signal to say it is running to raise the revs via the idle control valve. MS, with an idle control valve will sense a drop in engine revs at idle and compensate automatically, so no need for the input. The Lucas ECU does not give any signal to the AC system, it is pretty dumb in all honesty. Quote Link to comment Share on other sites More sharing options...
csimoes Posted August 12, 2013 Author Share Posted August 12, 2013 thnak's for the reply. in that case i'll be ok only with MS great. and what about the detail of the AC electric fans coming on? will it still happen? Quote Link to comment Share on other sites More sharing options...
AncientGeek Posted August 12, 2013 Share Posted August 12, 2013 I also live in a hot country where aircon is vital... On my 97 Discovery I removed the yellow-black wire from the AC logic relay, and put it on pin 86 of the AC clutch relay. You won't need the AC logic relay or the fan timer unit any more. Quote Link to comment Share on other sites More sharing options...
elbekko Posted August 12, 2013 Share Posted August 12, 2013 You could probably do the mod to have MS do fan control, and have them come on either when MS says so or when you turn on the AC. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted August 12, 2013 Share Posted August 12, 2013 I believe the AC fans are switched by a thermoswitch on the thermostat housing, but it would be possible to let MS control them or just wire the relay to the AC clutch as suggested. TBH the standard setup is simple & works so I'd leave it alone. Quote Link to comment Share on other sites More sharing options...
Mr Noisy Posted August 12, 2013 Share Posted August 12, 2013 See here for radiator can switch: http://www.elcome.co.uk/smpe_ecat/ViewPart.asp?p=50000&i=4711&pt=10&cid=129575374 It is M22x1.5 thread and fits in thermal housing as above, can be used for electric fan alone or in hot country as a backup for viscous fan. Cheers Quote Link to comment Share on other sites More sharing options...
csimoes Posted August 15, 2013 Author Share Posted August 15, 2013 ok. thanks for everybody's reply it looks that the simplest way is to just pacth it on pin 86 cheers Quote Link to comment Share on other sites More sharing options...
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