Operating Temperature/

[RayD]

Thanks Jay,

Thats where I started, following what you had said earlier.

Not wanting to trap the wire with the relay spade connector or solder one onto pin 85 I decided to look at the other end. It seems easier to do under the bonnet.

Looking at the diagram with an untrained eye it looks as though they will both run. I'm wondering if theres a diode stopping the flow to the pump......

Ray

[DeeAitch]

Thanks Jay,

Thats where I started, following what you had said earlier.

Not wanting to trap the wire with the relay spade connector or solder one onto pin 85 I decided to look at the other end. It seems easier to do under the bonnet.

Looking at the diagram with an untrained eye it looks as though they will both run. I'm wondering if theres a diode stopping the flow to the pump......

Ray

Only one will run. You will see that the fan relay has two outputs, one to the fans and one to the pump via its relay - so only one of these gets a live feed at any one time

[GeoffSmith]

Only one will run.

Correct! The reason for me saying connect to pin 85 is that the diode will block the manual switch from activating the cooling pump. The pump will still work if the temperature switch activates though.


So can nobody tell me what the pressure switch is yet?

[Monty]

pressure switch

[GeoffSmith]

On the circuit diagram on the previous page, there is a pressure switch. WTF is it?

[DeeAitch]

So can nobody tell me what the pressure switch is yet?

It's one of them things that connects two contacts, activated under pressure - as opposed to temperature for a temp. switch

You have PM

[RayD]

Geoff,

Its the ‘trinary switch’ in the air conditioning circuit - when a certain pressure is reached the cooling fans are turned on.

(See Air Conditioning section, in Mechanical manual)

Ray

[RayD]

Thanks Dave and Geoff,

To get it clear in my mind…

Geoff said fit the switch at Pos 2

I was going to fit it at Pos 1 thinking it was the same thing, but it looked as though it would energise the coil at 4

If there’s a difference between 1 and 2 presumably it’s caused by the ‘triangle’ at 3. Is this a diode? And if so, where will it be?

Excuse me if I’m missing something

Ray

[GeoffSmith]

Thanks Ray. Nice to confirm that I don't have one.

You're right. Number 3 is a diode and will only allow the current to flow in the direction of the arrow, so if you put a switch at position 1, the coolant pump will work whenever you have the ignition off. That's a recipe for flat battery if you ask me and why I recommended going in at position 2.

And sorry, I don't know where the diode is.

[RayD]

Thanks Geoff,

I'm now fully informed - I was only interested in the whereabouts of the diode on the off chance it was within the cooling fan relay casing which would put the kibosh on any simple manual switch.

Considering it shows it having a black and orange wire between the two items it must be a distance away.


Ray

[chris.t]

the elanscan run that i did showed that the fans cut in at 110 deg C. so that means that the coolant is under pressure (in order to stay a liquid) roughly half an atmosphere. This would obviously put additional strain on all the components in the cooling system (inc. the HG). I think an auxilliary switch would give you peace of mind especially if you haven't fitted your samco hoses yet

edit/ however i didn't say that the fans will cut out at 107 deg C.

[RayD]

I think an auxilliary switch would give you peace of mind especially if you haven't fitted your samco hoses yet

Chris,

Apart from a quick look at the Samco website the other day I haven't yet got round to finding why they are so popular...and so blue

What's the relationship between the Samco hoses and strain on the system?

Ray

[chris.t]

I think an auxilliary switch would give you peace of mind especially if you haven't fitted your samco hoses yet

Chris,

Apart from a quick look at the Samco website the other day I haven't yet got round to finding why they are so popular...and so blue

What's the relationship between the Samco hoses and strain on the system?

Ray

Ray, just thought if you still have the original 17 year old hoses on then how confident are you in them? The reference to Samco was that there was a group buy a little while ago and i know that some peeps haven't fitted them yet

[RayD]

Sorry Chris, I thought they might have special powers

While I'm here...

I’ve been to the scrap yard this week looking for three switches to replace the blanks on the dashboard, does anyone know where I can get some?

Thanks
Ray

[chris.t]

Sorry Chris, I thought they might have special powers

While I'm here...

I’ve been to the scrap yard this week looking for three switches to replace the blanks on the dashboard, does anyone know where I can get some?

Thanks
Ray

no worries Ray, better start another thread for your switches

[RayD]

See Clemo’s write up here.

Thanks to Geoff for his help with the electrics.

Having failed to find any original switches I bought two from Motorsave.

Soldered a wire onto pin 85 of the cooling fan relay.

Above the boost gauge on an SE there are three unused spade connectors, one of which is an earth in black. Ran the 85 wire to 1 on the switch and connected the earth wire to 2. That would have been the end of it, were it not for the lack of illumination on the LED.

Putting the wire from the relay to pos 3 and the earth to pos 1 lights the LED but the relay fails to operate.

As Geoff put it…

I think your switch is one that normally switches a battery supply to a load, whereas what you're doing is earthing the bottom end of the relay coil. By doing so, you're killing any voltage that would otherwise drive the LED or you're taking the relay current through the LED which makes it illuminate, but isn't sufficient to activate the relay.

There’s a chance applying a +12v wire to pos 4 may solve the problem, not knowing what effect it might have on the relay operation, I haven’t tried it.

I have it in mind to fit a separate inline indicator to show when the fans are running, once I find a suitable place to wire it in.

These switches were intended to be wired in this fashion…+12v to 3… load to 4…this gets the item running, fog lamp or whatever… then…putting a separate earth wire on pos 1 activates the LED in the on position.


Ray