Club 80-90 Forums

I was checking out the cooling fan on my '89 1.6 TD as it sounds really noisy when it does turn on, the radiator switch has 3 terminals live, and apparently speed 1 and 2, the 2 wires from the switch red/black and red/blue both join to one terminal on the fan the other terminal  on the fan is ground. my question is how can the fan be two speed with only one live terminal.
Dose anyone know where I'm going wrong. Cheers.

Yes it’s 2 speed , one live in 2 lives out , one for each speed

Yes 2 lives out but they join together on the one live fan motor terminal?

The way you describe it, it sounds like a two speed thermo switch, with a loom that has been adapted to fit a single speed fan.

But David is far more knowledgable than me.

My understanding is that the red/blue went from the higher temperature thermo-switch contact to a dual-stage fan relay, and then from the relay down to a third pin on the fan.

Three pin switch, three pin fan...
The lower temperature terminal feeds the fan via a resistor to run the fan at a lower speed.

Unless there is a series resistor in the wire in the low speed wire.

Obviously temperature 2 terminal to fan is without a resistor to run the fan at full speed.

Stirls2 wrote: ↑17 Aug 2022, 20:24 Yes 2 lives out but they join together on the one live fan motor terminal?

Got any pictures of the wiring

I'll try and get a picture tomorrow but the only way i could see how it could be two speed is if there was some sort of resistor but at the current that this motor draws it would need to be quite a resistor. brickwerks only have one fan motor listed for the diesel with just two terminals ground and live.

If the red/black and red/blue wires run from the thermo-switch straight to the same pin on the fan motor, then chances are that someone has simply bodged the wiring to suit the motor.

Correct wiring for two speed (2nd stage) radiator fan are:-

Switch...
Pin 1 - Red/Blue - 102°C switch to fusebox connector H pin 6 (H6)

Pin 2 - red/black - 92°C switch output to motor pin 1

Pin 3 - Red/White - Battery Live feed from fuse 1. (30amps). Fusebox connector C pin 7 (C7)
-------------------------------
2nd Stage Relay -

Pin 30 (Battery live) Internal connection within fusebox to Fuse 1

Pin 85 (Ground) Connector H pin 1 (H1) - 0.5mm brown wire to chassis.

Pin 86 (Relay Control +12 volts) 2.5mm Red / Blue wire - Connector H pin 6 (H6) to thermo-switch pin 1. 102°C switch output

Pin 87 (Relay Switched +12 volts) 2.5mm Red - Connector H pin 3 (H3) to radiator fan pin 2.
------------------
Radiator Fan Motor.

Pin 1 - 2.5mm Red / Black wire from 92°C thermo-switch output (switch pin 2).

Pin 2 - 2.5mm Red wire from 2nd Stage relay - connector H pin 3. (H3)

------------------
Series Resistor -

The radiator slow speed ceramic resistor is a similar size to the one for the heater blower motor.

If you have one, it would be tucked up on the 'shelf' behind the left headlamp, tucked right out to the side.

If you have a series resistor, it will be wired between thermo-switch pin 2 and radiator fan pin 1.
Both wires "should" be 2.5mm Red / Black wires.

I hope that helps.

I believe some early 3-pin fan motors had the resistor built into the motors themselves.



Connector H

Stirls2 wrote: ↑17 Aug 2022, 21:09 I'll try and get a picture tomorrow but the only way i could see how it could be two speed is if there was some sort of resistor but at the current that this motor draws it would need to be quite a resistor. brickwerks only have one fan motor listed for the diesel with just two terminals ground and live.

theres a resistor behind the left headlight

davidoft1 wrote: ↑17 Aug 2022, 23:38

Stirls2 wrote: ↑17 Aug 2022, 21:09 I'll try and get a picture tomorrow but the only way i could see how it could be two speed is if there was some sort of resistor but at the current that this motor draws it would need to be quite a resistor. brickwerks only have one fan motor listed for the diesel with just two terminals ground and live.

theres a resistor behind the left headlight

Only on the 450/500W fans (TD or 2.1)

ZsZ wrote: ↑18 Aug 2022, 04:43

davidoft1 wrote: ↑17 Aug 2022, 23:38

Stirls2 wrote: ↑17 Aug 2022, 21:09 I'll try and get a picture tomorrow but the only way i could see how it could be two speed is if there was some sort of resistor but at the current that this motor draws it would need to be quite a resistor. brickwerks only have one fan motor listed for the diesel with just two terminals ground and live.

theres a resistor behind the left headlight

Only on the 450/500W fans (TD or 2.1)

The ops is Turbo Diesel

Thanks Robsey thats the information I was looking for I'll do some investigating later and workout why I just have the high speed working

If you have the resistor, then either the resistor itself is tatered, or

the wiring may be past it - tarnished wires.
Or more likely any of the connectors along the slow speed circuit may be corroded or loose.

Or the switch may be pooped.

davidoft1 wrote: ↑18 Aug 2022, 06:54

ZsZ wrote: ↑18 Aug 2022, 04:43

davidoft1 wrote: ↑17 Aug 2022, 23:38

theres a resistor behind the left headlight

Only on the 450/500W fans (TD or 2.1)

The ops is Turbo Diesel

Sorry missed that

Here is the circuit diagram for the TD:
 

Thanks again guys I'm sure I'll get somewhere now

Quick update thanks to your help guys I diagnosed the problem to a bad fan motor, motor now changed and two speeds now working fine.
I had bought a fan from brickwerks this week but needed to confirm a few things, by the way the motor from brickwerks has smaller fan blades about 20mm shorter so I swapped it for the original fan already on the van.
Thanks again for your help