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Mk5 Golf R32 , black 3 door 2006
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Discussion Starter · #1 ·
Evening,
I the very near future , I plan to replace my radiator , all the hoses and plastic fittings, the ‘ crack’ pipe, thermostat housing and anything else on the cooling front that looks suspect . At the same time , I plan to remove my aircon condenser , compressor and all the associated gubbins ( wails of anguish from all O.E enthusiasts) so my question is what effect does /will that deletion have on the cooling fan operation as the low speed one wakes up if the aircon is activated. ? Ideally I would like both fans to come on once the water temp hits the switch temp ( which I guess is around 94/5) . In fact even more ideally I would like the fans to come on at 85 but that would mean a controller delete and an after market control. Any advice gratefully received
 

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It doesn't work like that.

The ECU controls the fan speed at anything from off to 100% - it can vary it to any speed it wants. It sends a PWM signal to the fan controller. There is no ON/OFF functionality.

The ECU receives signals from the AC over CAN and adjusts the fan speed to suit the AC, or adjusts it based on it's own maps and algorithms.

If you remove everything, fans will basically function as normal. The ECU will choose which fans to run, as it did before - based on engine temp, radiator outlet temp, ambient temp, speed, load, etc, etc. It's more about the radiator exit temp, than the actual engine - it just makes sure it has additional cooling available if required. There's no point in running a fan at 85C when the thermostat temp is 87C.

The ECU does a pretty good job of the fans. You'll hardly ever hear them, because they only run fast enough to acheive the required outcome. They can run at 50% for example, and be really quiet. It also does quite a lot of cooling at 50%.

Also, leaving it ECU controlled means the auxiliary pump can still run along with the fan, after shut down - that's fairly important, as the engine coolant temp can climb a LOT after shut down.

You can monitor the engine coolant temp in the Climatronic Secret Menu output 19-2. I use it often, especially when towing the caravan.

Sometimes, the ECU will run the fans flat out if it has a missing input, but that shouldn't affect you. The AC module will complain about the missing parts (compressor valve and pressure switch) but should otherwise function.

You'll probably get bored fast of the climate control trying to adjust with no AC though - you'll want to set it in "econ" mode so it doesn't try to blend in warm air with the "AC" air and manually control the fan speed etc. Be wary of it selecting re-circ too, because you'll get moisture build up in the car and foggy windows - was a pain in the arse when my AC packed up during the winter - I took the Land Rover on rainy days instead!

Is your AC functional now? If you're removing it to save weight, it doesn't make a huge difference - My new Compressor and Condenser in packaging was shipped as about 14kg according to DHL.
 

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Mk5 Golf R32 , black 3 door 2006
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Discussion Starter · #3 ·
Thank you . That was a hugely helpful and informative reply . Aircon functional at the moment but I want to save a bit of weight, change the radiator for an aftermarket one, fit an inter cooler and a supercharger ( and a 80 deg thermostat ) but will take your valuable advice and leave the rest of the system as it is and press the econ button .
 

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Supercharger is WAY more important than AC :ROFLMAO::cool: My R32 drivetrain is in my Touran, so it NEEDS AC as it's the Dad-mobile... but I think about forced induction quite a lot:love:.

If you're having it tuned (or running aftermarket ECU?) they should be able to fiddle when the fans come on... though it's probably not something they normally do to a Standard ECU.

You don't want to have them running excessively though... 1) they aren't that reliable anyway, 2) they get REAL noisy when running high speed.

It could be good to have them start up at around the "normal" temps, then ramp up faster, as the radiator outlet sensor goes higher - so it's just a shorter speed curve - full speed would be at a slightly lower temp. Maybe even altering the radiator outlet signal slightly could achieve that, without messing with fueling etc.
 

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Mk5 Golf R32 , black 3 door 2006
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Discussion Starter · #5 ·
Thanks . Car spends some time on the track ( but is still a road car really ) so cooling is quite important . Very interesting comments you make about the fans, their reliability , their noise ( quiet as church mice usually ) and the switch on and ramp up rate . I intend to stick with the O.E. Ecu so it really depends upon whether or not the fan controller management is user accessible . We have some very capable R32 specialists around in the U.K., as I am sure you do , so one of them may be able to help . My next job is to start there and see what they have to say .
 
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