The definitive heater modification

[Des Smith]

Ah, box of 10. I just looked at the picture... Still, I don't see me needing 8 spares.

[mat_fenwick]

Last time I had the dash out of my car, I traced the wire back that tends to loose the earth. It actually goes back to one of the pins on the heater resistor. It could be corrosion on a pin or inside the resistor that causes all the trouble.

That's what I wondered too, but didn't know. So if you link the pins on the PCB and it works as it should, you know the heater transistor (to be pedantic, not resistor) module is getting an earth - otherwise nothing would work, but not 'sharing' it with the control PCB.

[Dragon Man]

the one from my TZD Estate (with aircon) looks differant than the ones i have seen on here.. my one does not work in the full speed position (turned right up).. wonder if its a relay that has gone?

the scratched off track was already like it. its not a track though, its more like conductive paint between the tracks.

[Defender110]

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[Defender110]

No that is a standard one, there were a choice of 2 different types fitted the Chausson and the Eledas but both do the same thing, note the different contactors though.

[JayW]

the one from my TZD Estate (with aircon) looks differant than the ones i have seen on here.. my one does not work in the full speed position (turned right up).. wonder if its a relay that has gone?
2017-08-04 15.12.56.gif

the scratched off track was already like it. its not a track though, its more like conductive paint between the tracks.

I've seen no reference to the other type of circuit board, brand named CHAUSSON as opposed to the ELEDASA (Valeo) as pictured. Just wondering if it also has the same shortcoming as I've never heard the relay click when turning it to max? The pcb is in front of me but the circuits are not very clear, being covered by a protective white film of sorts .... hence unable provide a pic! This is off a K reg BX. Hope I haven't missed a previous posting asking the same thing

The plot is if the high speed relay is cutting in or not.
If you lean down to the steering column and hear a characteristic faint relay click while turning the fan blower control up, then there is nothing to modify.

If you dont hear that relay clicking and the fan does not kick into "hurricane" mode when the control is turned fully cw, then you need to modify.

It would be wise to turn off your 400Watts bass & drums before the test

[Dragon Man]

hmm interesting, thanks. theres an interesting thing that happens. when i turn the dial all the way to the cold the fans will work on full speed. but when i bring up the temperature enough to lift the little microswitch (which i assume is something to do with the aircon) the fans go back to very low speed on what should be full speed. ill have to go probing with my tester..

[Jaba]

hmm interesting, thanks. theres an interesting thing that happens. when i turn the dial all the way to the cold the fans will work on full speed. but when i bring up the temperature enough to lift the little microswitch (which i assume is something to do with the aircon) the fans go back to very low speed on what should be full speed. ill have to go probing with my tester..

That is sort of normal behaviour John. When temp is on cold you get full speed blowers - plus a gradual increase as the dial is turned. When not on cold i.e. the microswitch is out of the circuit the speed control should still work normally from slow to high speed but not quite as high speed as with the no heat position.
I think the idea is to give a bit of an extra blast when the aircon is on and no heat is required.
If the blower circuit board has been modded to get the extra speed it is possible to kill the normal speed control operation. Don't ask how I know this!!!

Great work by the way. Its very satisfying when the restore is all over and you get to drive the car at last.

[Kitch]

I've (now) got an unmodified Chausson one, and that does indeed operate the relay at full chat (on this car, anyway). The Eledasa ones don't, unless you carry out this modification.



p.s. Hi to people from the Facebook post that sent them here!

[Jaba]

That rather conflicts with previous comments above about the Chausson model. (Thought they were camper vans and they never go fast).

You seem to be combing through the old posts recently Kitch. Interesting.

[Vanny]

Needs to get a job, or a better hobby

[Kitch]

That rather conflicts with previous comments above about the Chausson model. (Thought they were camper vans and they never go fast).

You seem to be combing through the old posts recently Kitch. Interesting.

It does, and I'm not quite sure where those comments came from. My understanding was that the Chausson ones are wired correctly, and the Eledasa ones - for whatever reason - weren't. I've got an unmodified Chausson one (typically from the earlier mk2 cars) and it clicks the relay in and out. It's the only Chausson one I've ever had.

[Kitch]

Needs to get a job, or a better hobby

Haha! I need to declutter my life, but all I seem to be doing is taking more and more on! Definitely need a better hobby - DIY would be a useful one.

In fairness, this one was linked to on the FB post.

[bx-flynhi]

I wonder if this wil solve my problem - on BZ19GT there is what appears to be a relay under the steering column (RHD) that has a big blue and big green wire. When hooked up, the fan speeds up to full but wont turn off - it does go to lower speeds just not off.
When its unhooked, the fan will work but only on COLD ! when i move it to hot, fan stops.
SO i presume this is some sort of relay based on water temp ? Is this the same mod needed then ? Cheers

[Jaba]

Ah that sounds like a problem only aircon BXs could have. If so then it could be the earth fault that has been discussed quite a lot on here. Because as soon as you move off cold there is a small microswitch and lever behind the knob which cuts out the circuit through the high speed fan and the circuit then behaves like a standard BX.