Rad fan help

Back again, I got a new thermo switch and ran the car up to temperature and the rad didn't come on I have voltage to the switch , fan works when I bridge the connector. Fuse  is ok I can't figure out what is wrong 

Sounds like the thermostat in your water pump is not opening, so hot water never circulates around your radiator.

Do you think? I haven't looked  at thermostats, it has coolant flowing from the thin rubber hose to the reservoir bottle : 

gafo said

Back again, I got a new thermo switch and ran the car up to temperature and the rad didn't come on I have voltage to the switch , fan works when I bridge the connector. Fuse  is ok I can't figure out what is wrong 

Whats 'up to temp'?

On mine the lower rad hose only gets hot (ie the thermostat opens) when the guage is straight up. If left idling for 10 mins in summer weather the fan will eventually kick in and run for 1 min or so. Unless you leave it running you will never know if the system is working or not.

Does the car over heat and lose water before the fan runs?

I had it idling on the driveway, temp gauge was past halfway and the light was flashing. Didn't want to leave it running when light came on .Not losing water and fan doesn't come on 

gafo said

I had it idling on the driveway, temp gauge was past halfway and the light was flashing. Didn't want to leave it running when light came on .Not losing water and fan doesn't come on 

if you short the wires and make the fan run does it drag the temp down and stop the LED flashing?

does the bottom rad hose get hot before the LED flashes?

On the 90's cabriolet that I have driven, they all had a standard Bosch 40a relay (53) bolted to the right inner fender in front of the battery, this is the 53 relay I was referring to, when it goes bad as in Opens up your fan will never turn on.




Here is the typical non-a/c fan circuit.

I would say take it to the simplest of things (OLD SCHOOL)
Try this all it takes are a few wires and insulated connectors.
Run a wire from the battery Hot (12V+) to the left side of the Radiator Fan switch.  Out of the Radiator Fan switch  right side to the 12v High side of the Fan.  The left most Pin is Brown to frame ground.

You are using a 2 pin radiator Fan Switch?  or 3.

Here is the 90 wiring for a/c equipped cars with 2 speed fan.

What I am suggesting is the following. OLD SCHOOL


Will only take a few minutes to revert, No cutting wires.., Really old school see if it works this way.


 

Early 1800 , yes temp  gauge drops when I bridge the thermo switch. Bottom hose is hot no light flashing yet . Needle position 

Light just came on 

Brian I followed your instructions and I only got smoke from live wire cable not thick enough? What am I supposed to see? 

No air con in car and 53 relay is underthe dash , relay looks new and is hella brand , tried spare relay also

If bottom hose is hot thermostat is opening/working

the LED shouldn't flash until well over to the right of centre upright 12 oclock position, yours appears to be going off too soon?

the LED is also for low coolant level, is this triggering it? if your car is equiped with the sensor ontop of the expansion bottle remove the wire and short it, the circuit will then think there is plenty of coolant and shouldn't turn the light on.

You connect the Fan to the Switch on the radiator, then the fan switch other side to the + battery.  

It is a 30 amp circuit with 2.5 rated wire.  So I would use a 14-16 gauge wire if you use "american wire".

With the ignition running, the engine you will see 12V to ground on the battery side of the switch.  nothing on the other till it gets hot and turns on.  It will run until the water cools and switches off.

Cheers lads I really appreciate the advice , electrics just baffle me . Brian is this thing  with the cables a by pass or something? I don't understand what I'm supposed to be looking ?

I'm going to recap I think
Fan isn't coming on
New rad and fresh coolant
New thermo switch ..Tried two other oe switches
Power to thermoswitch
Rad fuse is good
53 relay looks new , tried a spare 
Light is coming on about half way on gauge 
Fan works when I bridge switch 
Coolant level is good 
Have taken  clocks out couldn't see anything obvious 

One thing I've seen in another post , I don't have earth wire from bulkhead to engine ( original engine replaced so didn't have the bits on it think it was in rocker cover )
Thanks again folks 

Typo( didn't have bolts on rocker cover)

From the rear right of the engine valve cover as you are looking at it to the firewall coil bracket, give it enough slack for engine torque.

gafo said

Cheers lads I really appreciate the advice , electrics just baffle me . Brian is this thing  with the cables a by pass or something? I don't understand what I'm supposed to be looking ?

I'm going to recap I think
Fan isn't coming on
New rad and fresh coolant
New thermo switch ..Tried two other oe switches
Power to thermoswitch
Rad fuse is good
53 relay looks new , tried a spare 
Light is coming on about half way on gauge 
Fan works when I bridge switch 
Coolant level is good 
Have taken  clocks out couldn't see anything obvious 

One thing I've seen in another post , I don't have earth wire from bulkhead to engine ( original engine replaced so didn't have the bits on it think it was in rocker cover )
Thanks again folks 

1. Fan isn't coming on as its not hot enough?
2. Light shouldn't come on half way up gauge but off to the right.
3. Missing rocker earth can give funny dash issues

With a multimeter set to continuity, test the thermoswitch. Should be open when cold and closed when hot (its a switch). No need to be running test live wires around the engine bay.

Short the wires on the expansion tank to see if its that thats triggering the LED

Does the LED flash with ign on and then off when engine starts?

It appears the fault is with the LED and not with the cooling system/fan itself

Ok, lets get Basic.

Does your fuel gauge work? Yes/no it is flaky?

Check and or replace the 10V stabilizer on the back of the cluster.

The Coolant tank does it have a big black nut in the middle of it with a plug?  yes/no.
Yes remove the sensor, and clean any and all corrosion off of the probe tips, replace.

Is your antifreeze to coolant 50/50 mix or straight a/f or water?  If it is straight anything the coolant level switch will be wonky all a/f and t won't light, Straight water and it will be on all the time.  It needs the specific resistance of the 50/50 mix.

Shorting the Coolant plug with wire will light the light in the dash.  It takes a 600 Ohm resistor to test the on/off of the plug IIRC.

No, disregard the above.

Water temp gauges are temperamental, flaky and  need to be looked at.

With your Temp Sender on the block, attack a 9V dc Battery to the Sender + side on the red/yellow wire and the ground to the engine block or brown wire.

Your coolant gauge should deflect to 3/4 scale and stay there.  Leave it on for 2 minutes (no key in ignition needed.)

Now if it doesn't deflect 3/4 to full, then you have some wiring issues.  So you remove the Bezel and tilt the clocks out of the dash.  Find the Studs for the gauge and directly feed it with a 9v dc battery if it doesn't deflect reverse the leads? Does it move 3/4 to full hot?

YES? wiring issues.
No, time to repair your gauge.
see:
https://www.volkswagenownersclub.com/threads/testing-digifant-water-gauge.32195/
see:
https://www.volkswagenownersclub.com/threads/repairing-your-flaky-water-temp-gauge.32211/

Now that you gauge is fixed,

The radiator fan is a Separate circuit.
It is a marriage between the Thermostat and the Fan Switch.

The t-stat and the Radiator Fan switch should be married that is a 95 degree  t-stat to a 95 degree sending unit.

the Radiator fan operation isn't controlled by a 53 relay.
it is controlled by a relay numbered 31 it is located on the fuse panel  pn is  #191955532A.

it is located in the upper row of the fuse panel.


You have verified that your system can be Irish engineered to run and that certain things are workable,
But I think you have a couple of issues.

First that your Grounds from the Engine to frame and frame to engine need to be upgraded or replaced.

Your Clocks have an issue that you need to address. they  are:
Plump the main connector.
Add an additional frame ground from the inner firewall to the Cluster wiring pin 2 brown.

If you did the clock tests you can do these additions at the same time.

Looking at the clocks and removing the water temp gauges and verifying it isn't flaky are 2 separate issues.  Look at the links I posted above.

T-stats and Fan Switches are known to be bad out of the box.  So you must test them prior to installing.

So have you heated them up to see the t-stat fully pop open?

Have you heated the switch up to see that it is closing or (shorting) electrically when up to temp?

When you drained to replace your coolant did you flush and back flush your cooling system with water to clean it out?

Water pumps with plastic impellers go bad more often that metal ones, but you would be getting boil over.

Test all the things and left us know.

Here is a better fused diagram.


 

Sorry for butting in on this topic but it is somewhat related.
I have also had to replace my original fan with a 2 speed, does anyone know if you can get a 3 pin female connector to replace the original 2 pin on the car?
Like Gafo I have just wired it in with crimps but would like a proper plug and socket fit.

 

3 pin

893906232 VAG - Cable connector 893 906 232 - 2407.pl Store

I would send them a email.