Thread: Temperature switch for thermofan wiring

How do you wire it the switch so it is negatively operated?

Switch I have is a Tridon TFS106
Normally open
95 on
90 off

Running two relays both with 30amp fuses.

I was running it with power to the switch but was advised against this as it earths through the readiator - current through water is not good.

If anyone can help that would be just fantastic .... wiring diagram would be most excellent.

Many thanks

David

That switch shouldn't earth through the radiator because it has two terminals. There will be no continuity between either of the terminals to the switch body.
I would connect like this:

1) Run a wire from battery +ve thru a 30amp fuse to #30 on relay (a normally open relay).
2) Connect #85 to one side of the switch (should not matter), then the other side of the switch to earth.
3) Connect a fused ignition feed to #86, this will give a power supply to the relay coil all the way to the switch...looking for a path to ground.
4) Connect #87 to fan motor +ve.

This is for one fan only. For two fans, just duplicate it and jump both #85 to one side of the switch. The closing/earthing of the switch (@ 95*) will trigger both relays, allowing battery voltage to flow between #30 & #87.

Alternatively………
Leave #30 and #87 as is.
Fused ignition feed to one side of the switch.
Other side of switch to #86 (to both relays for two fans).
#85 to earth (on both relays for two fans).

………either way you still have voltage at the switch, just a different method, but it will work exactly the same way.

Thanks Ski .... doing my head in it is .......

This was the current diagram .....

Have disconnected now ..... until I get it sorted .....


http://i597.photobucket.com/albums/t...currentDGL.jpg

David

Originally Posted by ski351

David,

Your wiring diagram will work fine...just needs one minor change. (this is same as my alternative way).
The red wire to the switch needs to go to a fused ignition "on" feed, and not connected direct to the battery as this will allow the fans to run when the ignition is off, till it drops to 90*.

There is no chance of any current through the radiator, because the terminals have no connection with the switch body whatsoever. Heating the switch just closes the contacts internally, all current will flow to wherever you connect the earth.....which is through the relay coil and then to the chassis.

I hope this makes better sense.

Cheers Ski ... I just reviewed my diagram and matched it to your instructions .... silly me .... I should have realised!

Thanks a lot for the assistance ... will rewire tomorrow ... woohoo!

David