!!ANDY!! 0 Posted March 23, 2009 Report Share Posted March 23, 2009 only been a member here a month or so, Bought a Mk3 VR6 Cab a few month back. To start off, i bought the car and the temperature gauge wasnt working,and the fans were not kicking in. i knew the electrics needed attention.Basically the two main looms from the fuse box to the engine and the engine loom had seen better days. I took all the looms out, and ive just swapped part of the loom that has the fan circuit on it for a good one. checked the other one and the engine loom over and i just need to repair a few parts of wiring that have torn and replace a few plugs.I still need to do the repairs but the car starts,runs....what i think is fine.The fan Plug on my existing fans is a 4 pin plug one earth, and 3 speeds. if i earth the fan and power each cable,the fan runs at the 3 different speeds from each cable. im plugged into the fan switch,but my new loom has a 3 pin plug for the Fans. One earth and 2 other cables. (2 speed???)Now if i start the engine,and let it run and warm up. connecting a multimeter to the new fan plug,i get 3 or 4 volts raising up to about 9 volts as the engine gets hotter. without the temp gauge im not sure how hot its actually getting,but all the hoses are really hot and im thinking the fans should be kicking in at this point!? it seems to get very hot but the voltage doesnt go above 9. ive got the 4 pin plug earthed to the new 3 pin plug from the fan controller, and tried all 3 speed fan cables to the cable with 9 volts coming through it and the fan wont spin up!??Im not sure how the circuit works??? wasnt sure if lower voltage would just spin it slower? or does it just send 12v down the appropriate cable to change the speed!??Now does the fan need full 12V to run? or would replacing the fan for a 3 pin one hopefully sort it? id have a complete circuit so to speak!? could the fan switch be the problem? (low temp one i was told by the previous keeper)I tested the Fan switch in a pan of boiling water. the water warmed up,reached boling point, and prob took a few mins before it switched. But it did switch!??Sorry for the long winded explanation,just thought the more info the better! Any help Mucho Appreciated. Andy. Link to post Share on other sites
thegoth 5 Posted March 23, 2009 Report Share Posted March 23, 2009 Fan speed doesn't increase with voltage, it's all or nothing.From my experiance the fan control unit needs 12v, or near enough, before it switches. I was only getting 8 volts at the switch and had to put in a new live direct to the battery. Link to post Share on other sites
!!ANDY!! 0 Posted March 23, 2009 Author Report Share Posted March 23, 2009 Ok thanks! thats just as i guessed to be honest. Id have thought the fan controllerjust sends a 12v signal down a certain wire for a speed depending on how hot the engine is! So doesnt really explain why im getting a variable voltage reading,going higher the hotter it gets,to the fan plug!?? if i should be getting all or nothing!?? Link to post Share on other sites
thegoth 5 Posted March 23, 2009 Report Share Posted March 23, 2009 are we talking about the radiator fan switch? There is one for the dash display, which will be variable, in the thermostat housing. Link to post Share on other sites
!!ANDY!! 0 Posted March 23, 2009 Author Report Share Posted March 23, 2009 Yeah rad fan switch is plugged in,and i think is working and does that send a signal to the fan controller!? the plug that goes to the actual fans, is the one im taking a voltage reading from,because thats what im wanting to power the fans! but that plug is 3 wires,one earth and two power. and my fan is 4 pin, has one earth and 3 speeds. Sorry,its really hard to explain. Link to post Share on other sites
thegoth 5 Posted March 23, 2009 Report Share Posted March 23, 2009 have you checked the voltage that's going to the radiator switch. that was what was low on mine. Link to post Share on other sites
!!ANDY!! 0 Posted March 23, 2009 Author Report Share Posted March 23, 2009 nope! will check that tomorrow...thanks for the reply. Link to post Share on other sites
!!ANDY!! 0 Posted March 24, 2009 Author Report Share Posted March 24, 2009 Well today i bridged two of the pins on the fan switch plug and it sends power to the fan plug. enough power to run the fan at any 3 speeds according to what speed wire i connect to the plug.So im gonna pick up a fan switch tomorrow and hopefully ill have it working at one speed at least. maybe it will cure it all,ill let you know.i bridge the other pin on the fan switch plug and nothing happens though!??? maybe it needs the fan switch to activate the other wire when it reaches a certain temp!??Ive read the rad switch runs two speeds,and the 3rd speed is controlled from the sensor in the thermostat housing.......i think!??As long as its cutting in on its own,even at hovercraft speed,im happy....for the time being! Link to post Share on other sites
Bobtrude 0 Posted March 24, 2009 Report Share Posted March 24, 2009 Is your thermostat working? MY went and the same things happened to me. Maybee its the same problem and nothing to do with electric at all?!?!?!When your car is warm. . . check that both radiator coolanthoses are hot. If not then your thermostat is shot! Link to post Share on other sites
!!ANDY!! 0 Posted March 25, 2009 Author Report Share Posted March 25, 2009 Yes mate. every single pipe in the bay gets red hot. if i power the fans,it cools down,the bottom hose getting alot cooler than the rest,as id expect.Im picking up the rad fan switch later,so will see if that cures it.Thanks. Link to post Share on other sites
!!ANDY!! 0 Posted March 29, 2009 Author Report Share Posted March 29, 2009 Fitted the fan switch and the fans are cutting in when it gets hot. But then they constantly stay on,even when its cooled down. if i switch the engine off,they run for a further 15-20 seconds then switch off! ????? Link to post Share on other sites
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