The definitive heater modification

Frequently asked technical questions and common modifications/improvements
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Des Smith
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Re: The definitive heater modification

Post by Des Smith » Sat Mar 14, 2015 1:23 pm

Ah, box of 10. I just looked at the picture... :oops: Still, I don't see me needing 8 spares.
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Re: The definitive heater modification

Post by mat_fenwick » Sun Mar 15, 2015 11:25 pm

David wrote: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.
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Re: The definitive heater modification

Post by Dragon Man » Fri Aug 04, 2017 3:19 pm

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.
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Re: The definitive heater modification

Post by Defender110 » Fri Aug 04, 2017 4:46 pm

DELETED
Last edited by Defender110 on Fri Aug 04, 2017 4:51 pm, edited 1 time in total.
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Re: The definitive heater modification

Post by Defender110 » Fri Aug 04, 2017 4:50 pm

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.
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JayW
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Re: The definitive heater modification

Post by JayW » Fri Aug 04, 2017 5:05 pm

Dragon Man wrote:
Fri Aug 04, 2017 3:19 pm
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.
Image

AndersDK wrote:
Tue Aug 21, 2007 10:54 pm
ed4ferrets wrote: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 :oops:
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.

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Re: The definitive heater modification

Post by Dragon Man » Sat Aug 05, 2017 1:44 am

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..
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Jaba
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Re: The definitive heater modification

Post by Jaba » Mon Aug 07, 2017 10:44 pm

Dragon Man wrote:
Sat Aug 05, 2017 1:44 am
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.
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