Radiator fan sensor

[Gapples]

Hi
I checked the operation of my radiator fan today and both speeds work fine.
The is according the instrumentation heating up rapidly as soon as I get stuck in any traffic.
The temperature will go from mid 80s at a steady 60 mph to high 90s at a standstill without the fan coming on.
I'm using the heater in the car and windows open method.

The problem I'm having is finding the sensor I require...
There are loads available but all are shown with connections in a straight line, either 2 or 3.
My connector has 3 connections set in a triangle
Anyone changed one like this or know where to source one please

It's a 92 two tone 1.7 non turbo.

[jifflemon]

Are you sure the fan isn't cutting in?

Its always one of the first things that i check, and the results can vary massively.

Seymour? Fan cuts in @ 104
Turbo? Fan cuts in @ 94
2.0? Fan cuts in @ 88

The takeaway isn't that there's different temp sensors, more that the displayed temp can be wildly different than expected, and what you need to know is what temperature YOUR fan cuts in at.
Its always a nerve wrecking task waiting for the fan to cut in, and you need to have a temperature in mind that you're going to say enough is enough, I'm switching off.

[Gapples]

Oh it does cut in eventually, usually the minimum it will cut in is an indicated 98c or there abouts.
I've seen start at 103c though, I'm not comfortable leaving it ticking over after a run out to see exactly how high it go.
Your right, it makes me very edgy to say the least, the car runs great and required I'll also fit a new radiator as the one on the car looks original

[Jay-Kay-Em]

Remember with a good rad cap holding 15psi the boiling point will be 125'c (ish) so your fan cut-in points are not alarming to me at least.

For peace of mind you can always put any sensor/switch (dash or fan) in boiling water with a thermometer + test.

IR thermometers are really cheap these days and have a multitude of automotive and DIY uses.

Until the header tank overcomes the cap pressure valve, there's no harm being done. You'll know when you're getting close as it will start making deep gurgling noises like a hungry belly.

For connector pin outs and the multiple fan switches available I use Autodoc. Not necessarily to purchase from, but to use all their pictures and part numbers. Different models have different fan temps and I know the Turbo has unique fan on and fan off values. Not that it really matters.

[Gapples]

I just did a test this morning after a run to get it throughly warmed up.
I left it ticking over and the fan kicked in at 101c...
It ran until the temperature dropped to 96c.

[jifflemon]

I’d say there’s nothing wrong with that. And now you know that, it means you also know that if it gets beyond 103 it’s time to switch the engine off.

[Jay-Kay-Em]

I left it ticking over and the fan kicked in at 101c...

If you have a three pin fan switch, and the fan is motionless until 101 then it appears stage 1 (low speed) is not cutting in.

Stage one starts much lower (starting at 93 ish) until stage two takes over at 101 (ish).

The importance of having that slower speed I don't know but Volvo must of thought it important enough. Fibreglass bonnet perhaps? Better hot starting?

If you only have a two pin connector I wouldn't be concerned.

This is all based on the instrument reading being reliable.

[Gapples]

It's definitely a 2 stage fan and both are working when loop the wires on the connector.
I suspect as you do the sensor isn't bringing on stage one but I'll fit a new sensor ( when I can actually find one ) and test again

[Gapples]

Well just an update to follow up...

Today I fitted a new fan sensor it's actually very similar to the old sensor in as much as the fan doesn't come on until about 99c/100c, the old sensor was 101c...
Well it's an indicated 100c, as previously stated by jifflemon the digital dash may not be so accurate, I'll leave it as it is now with the new sensor though. I'd be surprised if both old and new sensors were wrong ( although not impossible )

At least I was able to see the coolant was still lovely and clean and is now renewed anyway.

Thank again for your input guys.