Mk1 radiator fan

how can i test to see if my 83 mk1 rabbit fan works or if its a bad cable . 

Bridge the wires on the thermo switch the the fan should run or connect the fan motor directly to a battery.   

What I normally do is to test that the Brown wire is ground on the motor plug.  The motors are isolated and require a good ground.

I then check the motor on the car by placing (as you are looking at it) ground on the Far Left pin of the motor and jumpering the Far Right pin to the 12V+ of the battery, if the fan runs then cool it isn't the fan.  If it is a 2 Speed fan, 3 pins  on the motor or plug, the jumper the middle pin to 12V+ if it runs the Fan is good.

From there I test that the Radiator Fan switch has 12V on one side.  If it does then Bridge the connector spads together if the fan runs Great you have isolated it to the Radiator Fan switch being bad.

IF your radiator fan switch is bad, then you buy a new one and test it prior to replacing it.  

If there isn't 12V+ on one side of the switch, then you have a bad wire or bad fuse, Check the fuses first, then the wires, you can also jumper the Fan Switch to the Battery direct with a 30A inline fuse.

You can relay the Fan circuit between the Fan and the switch, then run two new wires to your dash and install a switch so you can turn it on of off at your leisure.

Relaying it shunts High Current from your dash, and allows you to straight wire it to the motor (via a inline fuse).

Replacing the radiator fan switch give you a good opportunity to Flush and Back flush your cooling system….

On newer Cabriolets with a/c they used a relay that sits in front of the battery off a bracket on the fender, but as yours is a 83, it is a tad more simple.

I checked the wires and i only have the radiator fan plug and there is no plug for the cooling fan switch could that be a problem i tried putting a paperclip

in the plug that goes onto the back of the radiator fan to see if it would jump but nothing happened i feel the paperclip was to skinny tho . The cars battery terminal

was was rewired and they might have ripped the connector for the cooling fan switch . I put some pictures to what cable is there and what cable isnt 
 

Well being that your radiator Fan switch is disconnected that could be an issue, I would think that the switch is bad, and instead of "fixing it correctly" the POS (previous  owners serviceman) re-wired it direct to a switch…..

Is that connector a 2 or 3 pin, as that would determine the switch that you would need.

Use a wire jumper set, and ground the left (as you are looking at it) the fan pin.  Then using a wire touch that to the +12V side of the battery and the pin on the far right (as you are looking at it).  If the Fan spins, then you know it is the "wiring being jacked (by the PO).

Your simple easy way is to buy a new radiator fan switch, unless you remove it and verify that in boiling water the switch shorts.  Installing a new switch or removing the old requires that you will drain the coolant.
TEST THE NEW SWITCH FIRST IN HOT WATER TO VERIFY THAT IT IS WORKING THAT YOU HEAR A CLICK AND THE TWO TERMINALS SHORT TOGETHER ON A METER.  Since it is 2pin, I would hope that you have a 2 pin fan.

Take some 14-12 Gauge wire, and a ring connector, Crimp it to the wire after stripping about 1/4 of an inch off of it.

Measure from the Battery Positive connector to one side of the fan switch for length and add about 1-2 inches of wire to the length.

On the other end of the wire Crimp a insulated female spad connector.  Connect it to the battery side of the switch (new one).  The other side of that switch take a length of wire that is from the switch to the Fan harness.  add a couple of inches.

Splice the new wire bitter end to the main harness (cut the usually red/white wire) Solder and heat shrink is best but you can also use a Butt-to-Butt inline crimp splice.  Now attach that free end to the open Terminal Radiator fan switch.

Verify that with the Fan plug connected that your Brown Wire is at Ground potential… If it isn't then you need to run a new ground.  This should resolve your fan not coming on issue.

THANKS TO EVERYONE WHO RESPONDS WITH SUCH GOOD STEP BY STEP SOLUTIONS IM NOT A MECHANIC IM JUST A TEEN WORKING ON MY OWN PROJECTS LITTLE BY LITTLE  TRYING TO UNDERSTAND WHAT PARTS YOU GUYS TELL ME TO START LOOKING TO FIND MY PROBLEM


IT TURNS OUT THE PREVIOUS OWNER WIRED THE FAN MANUALLY TO A SWITCH THATS LOCATED BEHIND THE CIGGARETE TRAY WHICH IS VERY HIDDEN . I NOW HAVE A PERFECT RUNNING MK1 RABBIT MY FIRST AS WELL . 

That's a very big battery fitted to your is it a diesel engine?

You could try and reinstall the thermo swtich wiring then you don't have to worry about flicking a switch when the car gets hot?

ReastOakland said

THANKS TO EVERYONE WHO RESPONDS WITH SUCH GOOD STEP BY STEP SOLUTIONS IM NOT A MECHANIC IM JUST A TEEN WORKING ON MY OWN PROJECTS LITTLE BY LITTLE  TRYING TO UNDERSTAND WHAT PARTS YOU GUYS TELL ME TO START LOOKING TO FIND MY PROBLEM


IT TURNS OUT THE PREVIOUS OWNER WIRED THE FAN MANUALLY TO A SWITCH THATS LOCATED BEHIND THE CIGGARETE TRAY WHICH IS VERY HIDDEN . I NOW HAVE A PERFECT RUNNING MK1 RABBIT MY FIRST AS WELL . 

I would get a new radiator fan switch as it is the OEM and never gave me an issue other than going bad over 20 years of Golfs and 15 of Cabriolets.  Also install a radiator card at the top of the radiator as it improves the efficiency of the radiator by 50 percent, bu not allowing engine compartment air to recirculate over the radiator.

Yes installing it would drain all the coolant, but at the same time you can flush and back flush your cooling system, and replacing the t-stat with one that matches the radiator fan switch is another reason to do it.  

If you buy the t-stat remember to buy the o-ring seal as well,   

Templates can be found at www.cabby-info.com

Cooling System

http://www.cabby-info.com/Files/Baffles_Top.pdf

How I flush a cooling system.(Cabriolet with a/c)
http://volkswagenownersclub.com/vw/showthread.php/21399-How-to-flush-your-radiator

Most of my how-to's are linked in the signature.

Easy to follow.