tropical radiator/ 2 speed fan

[marx3]

Hi, recently got one of those big radiators in my car, plus an original electric fan. Installed the relays and the wiring in the connector in the right corner of the engine bay, right under the coil.

Everything seems to work fine, but:

I can see that the fan will come on when the temperature on the head, measured at temperature sensor, hits 95 degrees celsius. Is this normal?

How does the 2 speed function? I have only seen one speed ( that comes at the 95 degrees )

Are the cooling capacity of this ( much ) bigger radiator so good, that the fan almost never has to run?

[SlowBrick]

Are you using the big volvo relay? It has two inputs for speed. If you only have one temperature sender then you are only utilizing one speed on the relay. Chances are your temp sender is ~95 on and ~90 off. Just change the value of your temp sender to change when the fan turns on. To use the second speed you can either have two switches with two different values, or one switch in the cooling system and one in the dash for the high speed.

[marx3]

yes I am using the original relay with two big wires going to the fan.
I still have the parts car that it all came from, will the engine in this car have two temperature senders ? I mean, how ever the 2-speed function is supposed to work from the factory, I could and want to do, since I should have all the parts for it...

Or?

A switch in the dashboard was a good idea though.

[945ti]

The fan works as follows:
Two small wires in the middle of the relay turns on the fan when connected together. Inside the relay im not sure what that means precisely,but I'd suspect that it completes the circuit to ground the cool on the relay somehow...

The relay then has a timer switch that will turn on another relay within the relay to power up the second winding in the motor for speed 2 after the fan has already been running for x minutes...5 or 10ish I think? In fairly cool weather with the big radiator and no a/c running at stop lights I doubt you will ever really see speed 2.

[krad]

If we are talking about ECU controlled e-fan then:

The engine fan is controlled by the ECU (and on some cars by relays) and has 2 speeds. The engine
cooling fan operates at low-speed if coolant temperature is above 102°C. The engine cooling fan
also operates at low-speed if the A/C-system pressure is greater than 17 bar on the high pressure
side and the speed of the car is below 100kph. The engine cooling fan operates at high-speed if the
engine coolant temperature (ECT-sensor) is above 115°C or the pressure in the A/C-system high
pressure side exceeds 22 bar. The engine cooling fan always starts at low-speed for approximately
15 seconds before it can operate at high-speed. It always runs at low-speed for 5 seconds when it
stops operating at high-speed. If the ignition is turned off when the fan is operating at high-speed it
will continue at low-speed for 5 seconds. So as not to overload the engine there is a delay which
prevents the fan from starting for 9 seconds after the engine has been started, no matter what the
engine temperature or A/C-system pressure. To cool the engine and avoid overheating, the engine
cooling fan will continue to operate at low-speed for three minutes if engine temperature exceeds
105°C when the ignition is switched off.

That's how it should work from the factory.

[945ti]

^i think that may be an s/v/c and later car. 940s I'm pretty certain only complete the one ground circuit on the relay because Regina cars use the same relay and have the two middle wires going to a simple temp switch on the radiator to close the circuit is all I remember seeing. I don't remember, what it anything those bendix/Regina cars do for running the fan for a/c...I don't remember them using a high pressure switch that shared with the radiator temp sensor, but you would think the fan would somehow be triggered with the air. I'm pretty certain I hooked up that flag for long enough that t would turn on the high speed after so many mins a long time ago.

The ecu does control the fan on the Bosch lh-jet 940s, that is definitely true, but I'm pretty certain it only controls on/off, not hi or low.

[krad]

Are we talking about LH 2.4 or Regina car? OP has LH 2.4 car. I've attached one specific page from green book (LH2.4 EZ 116K.pdf) file where they describe how it works. They mention that this applies for 92 940 with AC but according to people on this forum all 9xx ECU's has that feature.