dave t Posted January 6, 2012 Share Posted January 6, 2012 Would it be possible to wire in a switch to manually control the aircon fans (300tdi) for engine cooling? and if so what the best way to do it, just run a switched power supply to the fans relay? thanks Dave Quote Link to comment Share on other sites More sharing options...
dave t Posted January 6, 2012 Author Share Posted January 6, 2012 Would it be possible to wire in a switch to manually control the aircon fans (300tdi) for engine cooling? and if so what the best way to do it, just run a switched power supply to the fans relay? thanks Dave Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted January 6, 2012 Share Posted January 6, 2012 Why do you want to do this? But yes, investigate the relay connections and hwo to trigger it, and connect a switch to it. Quote Link to comment Share on other sites More sharing options...
dave t Posted January 6, 2012 Author Share Posted January 6, 2012 Why do you want to do this? But yes, investigate the relay connections and hwo to trigger it, and connect a switch to it. I run without the viscous fan and 99% of the time its not a problem but it would be nice to switch on some engine cooling if I needed it and its much cheaper and neater than fitting a kenlowe or suchlike Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted January 6, 2012 Share Posted January 6, 2012 Worth pointing out the aircon fans are only up to the job of cooling the aircon condenser, not the engine. May work as an extra boost to the viscous but not to be relied upon on their own. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted January 6, 2012 Share Posted January 6, 2012 Yep ^^^ Plus the air con fans come on anyways once the coolant temp leaving the engine hits 105C -that's the temperature that the switch on the side of the thermostat housing turns them on, regardless of air con switched on or not. Personally I'd leave alone, if you have cooling problems, fix the problems, don't mask the issue by putting more fans in front of the rad. Quote Link to comment Share on other sites More sharing options...
dave t Posted January 6, 2012 Author Share Posted January 6, 2012 I dont have cooling problems I was just considering the possibility of getting stuck in a traffic jam and having to sit or crawl along for a while, Without the viscous fan the engine could overheat. so are you saying the aircon fans wont bring the temp down in a situation like that but a kenlowe (or such) electric fan will? of course I can just refit the vicous fan and forget about it but I dont want to! Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted January 6, 2012 Share Posted January 6, 2012 A proper electric fan will set you back all of a tenner from the scrapyard. The AC fans may bring the temp down sat in traffic as the TDi is over-cooled and ticking over it's not generating a lot of heat, but they aren't up to shifting the air that a proper electric or viscous can. Quote Link to comment Share on other sites More sharing options...
dave t Posted January 6, 2012 Author Share Posted January 6, 2012 A proper electric fan will set you back all of a tenner from the scrapyard. The AC fans may bring the temp down sat in traffic as the TDi is over-cooled and ticking over it's not generating a lot of heat, but they aren't up to shifting the air that a proper electric or viscous can. Ok thanks for that I assumed they were just normal electric fans but blow rather than suck and there is two of them! I used to run my 300 tdi engined range rover without a fan and I got stuck on the m5 for two hours on a hot summers day and the engine started to overheat, fortunately I used to carry the viscous fan in the back so I just pulled over to the hard shoulder and spun it on. I will try the aircon fans on a switch and see what happens thanks for the help guys Quote Link to comment Share on other sites More sharing options...
mickeyw Posted January 6, 2012 Share Posted January 6, 2012 I can't imagine you will have the problem you expect. A 300tdi in creepy crawley traffic is more likely to cool down than overheat. We towed a challenge truck behind a heavily laden 110 all the way from Cornwall to Sussex, on a hot summer afternoon with no fan fitted to the 110. It did get slightly near the red on a couple of long 2nd gear drags on the A303, but nothing that caused us to stop. Now if you were talking V8s, that would be another matter altogether Quote Link to comment Share on other sites More sharing options...
Pinn76 Posted January 6, 2012 Share Posted January 6, 2012 Our RRC challenge truck (v8) is running 2x air con fans instead of a viscus one. Not had any cooling issues at all while compeating all day. Quote Link to comment Share on other sites More sharing options...
dave t Posted January 7, 2012 Author Share Posted January 7, 2012 Our RRC challenge truck (v8) is running 2x air con fans instead of a viscus one. Not had any cooling issues at all while compeating all day. Are they sitting in the standard aircon position? and how do you have them hooked up? manual switch or stat? thanks Dave Quote Link to comment Share on other sites More sharing options...
JimAttrill Posted January 10, 2012 Share Posted January 10, 2012 Yes, I reckon you could do that. I have a single Disco a/c fan mounted in front of my Defender (which didn't have an a/c fan as standard). It seems to improve the a/c performance at slow speeds. Though on the other hand I just fitted it because it was lying around in the garage I wired it into the rear window demister as I never use that. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted January 10, 2012 Share Posted January 10, 2012 This seems to be a duplicate thread: http://forums.lr4x4.com/index.php?showtopic=73587 Quote Link to comment Share on other sites More sharing options...
teabag Posted January 11, 2012 Share Posted January 11, 2012 Just parallel wire a switch into the terminals of over temp sensor that's screwed into the thermostat housing. Job Done. Quote Link to comment Share on other sites More sharing options...
teabag Posted January 12, 2012 Share Posted January 12, 2012 Just parallel wire a switch into the terminals of over temp sensor that's screwed into the thermostat housing. Job Done. Ooooops, it apears that the fans only operate with the is engine switched off, so it's now not as simple as justadding a parallel switch. Copied from a workshop manual: "It should be noted that under high coolant temperatures, when the engine is switched off, the condenser fans will be activated and will run for approximately ten minutes." Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted January 12, 2012 Share Posted January 12, 2012 That's not 'only' with the engine off, they operate when it is running as well, under high coolant temps -I know this because it's what mine used to do. So... it is as simple as above. Quote Link to comment Share on other sites More sharing options...
SPendrey Posted January 12, 2012 Share Posted January 12, 2012 Without meaning to drag this thread off in a different directions... I've just installed a fan with a Kenlowe controller, and there is an A/C feed which forces the fan on when the A/C is switched on. Now, I can understand this is the temps are >105C which is when the A/C fans automatically switch on, but does running the A/C generate addition 'heat' in the engine? Is is just the additional load it creates in turn forcing the engine to work harder to maintain speed? I guess its that last one?! Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted January 12, 2012 Share Posted January 12, 2012 The AC condesnser is condesnsing gas back into liquid(as I understand it, if not then cooler gas), so from your basic physics you should know that a lot of heat is given out at the point, this heat is then thrust into the engine bay through the radiator somewhat diminishing the performance of the engine radiatior. Extra engine heat will also be generated just by the fact the engine is running the compressor. Think of the AC system as a giant fridge, ever felt the back of a fridge/freezer running full tilt? They get very warm. Quote Link to comment Share on other sites More sharing options...
Disco1tdi Posted January 12, 2012 Share Posted January 12, 2012 Whenever you hit the A/C button, the fans kick in. They also kick in, when the engine coolant temps get to a certain point. I've seen this in action, but it's only ever happened during an MOT, and I've removed the viscous fan. Quote Link to comment Share on other sites More sharing options...
teabag Posted January 12, 2012 Share Posted January 12, 2012 To true, extra engine heat will also be generated when a/c is on, just feel the heat blowing out of the front wheel arches on a hot day. On a hot days with the a/c switched and in traffic on I can hear the sound of the viscos fan change as it locks up it's the same 'turbine' sound that the fan has on starting from cold when driving for the first 300 mitres or so, it just proves how hot the radiator/engine is getting, that's for a D1 V8 though. Only the D1 a/c fans run when the a/c is switched on, the D2s single fan is automatic so is running as required much like most modern cars today Quote Link to comment Share on other sites More sharing options...
teabag Posted January 12, 2012 Share Posted January 12, 2012 That's not 'only' with the engine off, they operate when it is running as well, under high coolant temps -I know this because it's what mine used to do. So... it is as simple as above. Looked through Rave again and in the a/c section under operation it is stated: "The cooling fans are controlled by engine temperature when the air conditioning is not switched on." So indeed back to the parallel switch idea. Quote Link to comment Share on other sites More sharing options...
Fossy31 Posted January 12, 2012 Share Posted January 12, 2012 You could use a switch or do what i have done on both discos, assuming you dont acctually want the aircon on! I have disconnected the air con compressor by unplugging it, then you can manually turn the fans on by pressing the snowflake button and turning the heater fans on, this puts the aircon fans on constant. If you want to turn them off just turn the heater fan off or press the snoflake button again. Simples! Quote Link to comment Share on other sites More sharing options...
Pinn76 Posted January 12, 2012 Share Posted January 12, 2012 They are sat in-front of the rad on a diy bracket and wired to a switch with warning light on the dash telling us we've not forgot to turn them on. We find that by having them on a switch we can shut them off if entering any deep water. Yes, we did forget to turn them on once, took a good 1/2 hr to get on the warm side so shows they are up to it. Air flow is really good as they will suck in and shred the odd leaf every now and then. HTH. Bri Quote Link to comment Share on other sites More sharing options...
dave t Posted January 18, 2012 Author Share Posted January 18, 2012 So adding a switch in parallel means you just bridge/short the two sensor contacts right? my stat housing has two sensors I am assuming one for the temp gauge and one for the AC fans, any idea which is which thank for all the advice guys Dave Quote Link to comment Share on other sites More sharing options...
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