Diode in heater fan controller?

And came from a Citroen apparently (I had another quick look as I went past earlier).

It is basically a 40 x 40 x 50 mm long open ended square tin 'tube' with 3 wire 'resistor' coils within said frame near the connection plug (looks like it plugs in like a relay or module) and this 'device' (thermal fuse) sits longwise within this tube and slightly nearer the side opposite the resistors.

So, if it was orientated with the connector facing down, any hot air off the resistors would tend to be blown through the tube and away from the device (or not if the air wasn't moving fast enough).

Cheers, T i m

Yes I think, but because it's in this sorta tin frame (and crimped in at that) you would have to either cut it out or be lucky to get it a the right angle with a magnifying glass to be able to read it.

I printed off the info from the link that Paul gave earlier and gave that to my mate.

But as Chris mentions previously, 'repairing' an otherwise un-repairable item could have implications should it ever be proven to be the cause of an issue. Obvious when working on the brake system but maybe no so when fixing a heater?

*Personally*, I wouldn't hesitate repairing (or redesigning) such a thing on my own vehicle and if I knew I was going to run it into the ground as I know I would do it safely and no one else would have the risk in any case.

Thanks for all the thoughts, help and advice though guys. ;-)

Cheers, T i m

p.s. I think this interest was just that, interest. What is this component, why does it fail and could it be replaced etc. I think the whole assy new is under 30 quid and whilst in the old days (or many other countries today ) it would be repaired, these days (here) there are other implications.

The job of a diode employed to prevent back EMF isn't to disperse power.

It wouldn't.

This refers to Citroen heater packs having thermal fuse

which in turn refers to which shows a 15mm by 4mm device with red end....

its a thermal fuse, QED ;-)

Of course it is, the motor is generating a current/voltage/power, whatever you want to call it - this will backfeed into the control electronics unless given an easy path to disperse. See also relays.

So you can either connect a diode directly across the terminals of the motor, or you can run some leads some distance away to a pcb, or hidden away in a duct..no.

Anyway, its a thermal fuse - proved in other thread.

[...]

Unless using it to reduce radiated interference, when it needs to be as close as possible to the inductive load of course.

Chris

Yup, that's just what it looks like.

Interesting additional info as well, like crimping a replacement onto the existing wires (hence not disturbing their mounts to the base etc).

Yup. ;-)

Thanks again, T i m

Wimp. Real men solder thermal fuses in place. ;-)

That may as be but my BT soldering training said that an electrical joint should (ideally) be a mechanical one first. ;-)

Also, I'm never sure when using solder around 'hot things'. Whilst I hope the temperature in this fan controller never reaches the point where it could melt solder (if it does it probably means the car is already on fire) with it also being thermally sensitive etc etc ..

But yes one could form a mechanical joint first (form small loops in the end of each wire and nip up) then solder to maintain a good low resistance connection.

Cheers, T i m

components such as the one under discussion tend to have welded joints rather than soldered. It is difficult to solder onto the hard wires that are used. I would use two tiny screw on connectors to add the thermal fuse. I have also used these to rejoin fan heater elements and they have lasted indefinitely.

'Twas meant as a joke. If you solder a thermal fuse in the normal way it will blow. ;-)

Unless its a thermal fuse in a soldering iron ;-)

You can solder thermal fuses but you need lower temperature solder and a big heatsink which is not something the average bodger has knocking about the garage

depends on the fuse temp. to some extent too, I soldered in a 130 degree one into a halogen lamp dimmer switch without problems a while ago.

You are not the average bodger though are you

Conor formulated on Wednesday :

Oh yes it is.

Oh yes it would.

You can get very high voltage spikes too

Or crimped in this case.

Ok.

Like the 'guts' out of a section of 'chock block'?

Talking of that ... the last time I connected to such it was about 8 strands of 'Eureka wire' (from an electric bar fire) that were twisted together then formed into an open coil and fastened under brass washers on big brass bolts.

Stick it in first, twist the throttle to position 1 and the stalled motor is fed 24V via my 'resistor' (now just starting to glow dull red) and as soon as the current drops back then twist to position 2 (resistor bypassed). Back to position 1 and into second etc etc till I was holding an average for 25A round the lap. (Batteries had a reserve capacity of 25Ah and the 'race' lasted 1 hr).

The MIRA long track is very long at those speeds. ;-)

Through that I met the guy who went on to do this:

Cheers, T i m

(My 'Electralite' was a stretched motorcycle design.)

Just out of interest, has anyone ever personally known an insurance company to check for anything like this?

I have a feeling there are people out there who think that assessors are forensic scientists sent to inspect every single part of a car in the case of a claim. They do get a bit serious if someone is killed because of a mechanical failure, but I've never known one to look any closer than "Car is burnt out, and it's not obviously been torched".