VS Commodore V6 Thermo Fan High Speed or Low Speed Question

[DexterVS]

Hi All,

I can't quite find the answer to this question anywhere, so hoping someone can help me.

The thermo fan activates only when either Air Con is on or when the temperature needle reaches near H. I have recenly flushed the cooling system and replaced both the temp senders. this has not changed the behavior of the fan.

I was monitoring my engine the other day using the ALDL cable and software blah blah. I noticed that the program would say the "low speed" fan is the one that activates when the needle is almost at H. i think the coolant temp reached about 109 degrees....

does this sound like it is behaving correctly? What scenario will activate the High speed fan?

 

[Immortality]

No. Low speed fan comes on at 104°C, high speed fan 109°C

 

[DexterVS]

No. Low speed fan comes on at 104°C, high speed fan 109°C

Hmmm interesting.

So if that is the case. Where should i start looking to repair this scenario?

Monitoring the ECU, it never came up saying that the high speed fan had been requested to activate. Only the low speed.

 

[Immortality]

Monitor the actual engine temp and see what does and doesn't work. If the low speed fan isn't working test the relay and thermo fan circuit.

 

[DexterVS]

Monitor the actual engine temp and see what does and doesn't work. If the low speed fan isn't working test the relay and thermo fan circuit.

So this is then a more import question i suppose….
When i do monitor the engine, i only ever see the “low speed” fan turn on. (Computer software says it is the low speed fan) i never have the high speed fan turn on. (According to the computer)

Also i haven’t ever noticed any difference in fan speed between fan from air con being on and fan being running because I’ve sat idle for a long time.

How can I be sure which is high speed and which is low speed?

 

[Immortality]

The aircon triggers the low speed fan.

You can pull out the high speed relay and then use a piece of wire with a couple of spade terminals crimped onto each end to trigger it manually and then you'll know if it works.

Alternatively you could let the car idle, pull out the low speed relay and then let it get hotter and see if the high speed fan triggers on.

 

[ephect]

Unplug the plug from the 2 pin temp sensor.

Put the ignition to reds or start the car, I cant remember which works.

The low speed fan should activate after 5 or 10 seconds.
Then the high speed fan should start 5 seconds after that.

This will tell you if both speeds are working or not. Then you can fault find from there.

 

[Immortality]

Never knew that.

 

[DexterVS]

Unplug the plug from the 2 pin temp sensor.

Put the ignition to reds or start the car, I cant remember which works.

The low speed fan should activate after 5 or 10 seconds.
Then the high speed fan should start 5 seconds after that.

This will tell you if both speeds are working or not. Then you can fault find from there.

So i unplugged the sensor, fan came on, and then, yes the fan kicked it up a notch. However, i would say that the variation in the speed wasn't that noticeable. just made a slightly different noise haha.
Anyway, it does help me with understanding whats happening within the cooling system.

I'll monitor the engin again when sitting in traffic and see what temperature the low speed turns on at.

But while we are here, IF there was a problem with the low speed turning on at too high a temp, how does that get rectified? Its all done via the programming of the ECU right?

 

[Immortality]

Yes it all runs off the 2 wire sensor. The dash however runs off the single wire sensor.