volvo fan relay setup for 2 speed fan

[Daze57]

have a couple questions about this set up

[Daze57]

vettevet

best way to hook up led lights as which one is on and which one is off
this is a 2 speed fan set up

and is it ok to use a circuit breaker insted of a 30 amp fuse between relay '30' and the battery

finally figured out how to post picts -------about time eh?

[VetteVet]

Here's my reply in our PMs earlier in the day.

This is a very interesting question but I need some clarification.
I think you are using one sensor, and one fan motor and one 50 amp relay. Is this in operation or not yet?

You would need two separate ohm grounding sensor values, which the Volvo sensor may be.
The relay if only one, would power both fan speeds at once.
87A is normally closed, so when the relay engages there would be no power to the fans,
but the relay will run the fan whenever the power wire to 30 is connected.
I would think you would need two power wires to the fan one for each speed unless the one power wire is using resistors to slow the fan from separate power sources.Does the sensor have two wires to connect to the relay?

Your LEDs need to connect to the power side of the relay which feeds the fan (87) but they would both be on any time the relay was energized. If you had two power wires going to the fan then you would connect the LEDs to the two power wires Green light to low speed wire and red to high speed wire.

You might also be able to connect the LEDs to the sensor if it has two feed wires to the relay. These would be on the grounded side of the LEDs and would be switched on the ground side and you would run a hot key on power wire to the Positive side of the LED. Remember the LED is polarity sensitive so they have to be wired correctly.

If you wanted to post in the electric forum we could get some diagrams and pictures as well as input from other members. I want to know these answers too.
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Your diagram above shows an example of what my reply covers.

It shows one relay which controls two relays for fan speeds.
It shows two power leads for the fan One for low and one for high.
It shows a dual control thermal sensor-one terminal for each fan speed.
You have a switched relay to control the two fan relays which is ok but a key on hot wire to the control relay would remove the possibility that you forget to turn the control relay on.
You would have to wire in the positive side of your LEDs to whichever fan speed wire you wanted the light to reflect the fan that was running.

Did I give the answers that you need?

This setup would allow the use of only one fan as long as it was capable of cooling the engine coolant temperature and possibly replace the need for another fan to cool an AC equipped truck.

[Daze57]

sir ---
all your answers make perfect sense -and i will follow the course
last question - is it ok to use a circuit breaker from relay ''30'' to the battery
in place of the 30 amp fuse?

as usual your help is v v much appreciated
thank you v v much ---very glad you are on this board .

dave

[VetteVet]

It depends on how much amperage the fan pulls, usually on startup it's the greatest. I like the slow blow maxi fuses for that type of application. A circuit breaker is used by a lot of the guys and it makes sense because you'd get the function back as soon as the high draw was done. Either fuse type is ok as long as you carry a spare. If the fan motor fails it won't make much difference which one you use. The CB or the Maxi-fuse is a better choice than the normal fast blow type.

[MARKDTN]

I know this is an old post but I came across it today. Someone may want to reference it in the future. I have done 2 of these Volvo relay type conversions and can share some thoughts. It is a pretty simple way to get 2-speed fans with no computer and no probes. The diagram is good in general.

The temp switch to use is from BMW. There are 2 variations depending on how hot you want it to be when the fan first comes on and ramps up.
61318361787--BMW temp switch 180*/195*
61311378073--BMW temp switch 195*/210*
(note that these use 14mm threads. So you need a 14mm female to 3/8 male adapter which you can buy or make it from a common 3/8 male to 1/4 female fitting and a 14mm tap)

If ordering new you also need these parts for a connector:
61131378410--BMW straight connector
61130007441--BMW straight green connector wires - 3 required
You can try to find these in a salvage yard with the sensor but these connectors are brittle, I would source it new.

One of mine runs a single 3.8 Taurus 2 speed fan while the other used a '00 Contour dual 2 speed fan setup. I use a 50A circuit breaker for protection and a 70A Hella (or Bosch) relay to kill power so the fans stop when the when the ignition is off. I use ignition power to the trigger on the relay in the diagram and no switch. Hope this helps someone someday.