The definitive heater modification

Frequently asked technical questions and common modifications/improvements
User avatar
electrokid
1K Away
Posts: 1764
Joined: Fri May 09, 2008 2:14 pm
Location: Woking

Post by electrokid »

EJX is the code for Furio red - which is slightly darker than Venetian red. The actual colour of your car should be written in the space provided in the original owner's handbook. There are cars with EJX under the bonnet which may be in Furio or in Venetian - but if you use the wrong one to touch up blemishes the difference will be obvious.
1992 BX19 TGD estate 228K Rusty - SORNed
2002 C5 HDi SX estate
Grgabx
New Member
Posts: 8
Joined: Sun Mar 29, 2009 10:30 am

Re:

Post by Grgabx »

jeremy wrote:The circuit board is in the earth return circuit - ie the circuit is through the ignition switch, through the component (ie blower motor etc) through the plug into the circuit board thence to earth.

So you have earthed the control coil of the max speed relay (click) and the blower motor - so that part of the car wiring is OK. Working from the right on the circuit board terminals 2 and 3 are connected together on the board and are earthed - terminal 1 is the panel light.

If none of the 3 functions work (panel lights, max speed and blower motor) then there may be a general board fault but this is unlikely as the whole thing is so simple.

If the panel lights only work then the chances are that there is a problem with the small 'wiper' situated under the rotating disc has been lost or displaced. Its function is to join 2 segments under the rotating part of the switch together and complete the circuit. If this is missing I'd still expect the panel lights to work subject to what I said in my earlier post (namely with good bulbs etc.)

Hello guys after a long time. first of all I wish you Merry Christmas. Second, i quoted this post because I have problem with control panel. I thing I have lost the small "wiper" under the rotating disc. Can anyone tell how does it look(does it have 2 bumps for each circle?) and how can I make it out of copper plate i have.
I also mede modification but haven't try it yet because of this metal plate. And the bulbs drop dead long time ago. I'm thinkong about LED displacement. Is it available somewhere?
Thnx
Drive with style
User avatar
mat_fenwick
Moderator
Posts: 7328
Joined: Tue Sep 20, 2005 4:08 pm
Location: North Wales
x 20

Re: The definitive heater modification

Post by mat_fenwick »

There is a thread on here some about replacing the bulbs with LED drop in replacements, which are readily available from eBay and the like. Depending on which type you go for there are issues with brightness and directionality, and the dimmer control will have little effect.

The contact under the rotating disc can be one of (at least) two types. There is one made from a springy metal strip, with (IIRC) two bumps to make contact with the PCB. The other type I've seen looks a little like two balls joined together. This uses two tiny springs to keep contact with the PCB, which can go missing!

If you're struggling to make something, I have a spare modified PCB which could be available.
Image

1993 1.9 TZD Turbo Estate
1996 3.9 V8 Discovery
1993 VW LT35 campervan
1985 Hyundai Stellar V8
2016 Hyundai iLoad
Grgabx
New Member
Posts: 8
Joined: Sun Mar 29, 2009 10:30 am

Re: The definitive heater modification

Post by Grgabx »

thaks for the note. I will first try to make this plate with spring improvisation. Actually i will try to connect this two circles to se if the blower works at all after this modification.If it doesn't work I'll let you know.
Drive with style
Grgabx
New Member
Posts: 8
Joined: Sun Mar 29, 2009 10:30 am

Re: The definitive heater modification

Post by Grgabx »

I've tried with small wire. the speed was increasing but when I jump to last part of circle the blower didn't woork. That part was over connected as described in this posts. I also suspect that only one fan works. I will probably take them out and check and clean. It shouldn't be a problem. A few screws and connectors. Do I have to take out the wiper motor out first?
Drive with style
User avatar
mat_fenwick
Moderator
Posts: 7328
Joined: Tue Sep 20, 2005 4:08 pm
Location: North Wales
x 20

Re: The definitive heater modification

Post by mat_fenwick »

Two motors - do you have air conditioning then? If you do you will probably find that there is a switch on the temperature control dial which only enables the full speed relay when set to fully cold. If the contacts in this are dirty you will never get full speed.

You don't have to remove the wiper motor itself but you do have to take off the arm and plastic vented panel beneath it. You should be able to tell if both motors are rotating by ear though.
Image

1993 1.9 TZD Turbo Estate
1996 3.9 V8 Discovery
1993 VW LT35 campervan
1985 Hyundai Stellar V8
2016 Hyundai iLoad
Grgabx
New Member
Posts: 8
Joined: Sun Mar 29, 2009 10:30 am

Re: The definitive heater modification

Post by Grgabx »

I do have air condition that is installed after and it contains two buttons installed in konzole nera handbrake. one is for turning ON the air-con and other is closing the air channels in ventilation-recalculating air.
Drive with style
frommbold
New Member
Posts: 1
Joined: Sun Mar 31, 2013 6:10 pm

Re: The definitive heater modification

Post by frommbold »

(soory my english - its hermann the german writing)
after overhauling and checking my heater system, my conclusions to this mod:

- the increase of ventilation energy by reducing the residual resistance of the transistor is nearly not to realise. the effekt is less than two drops of oil on the bearings of a 20 year old vent motor or its cleaned collector.

- if you realize an major increase of ventilation by this mod, it is not caused by the residual resistance of the transistor. its caused by a switched resistance of the transistor. the reason for this switch is shown here:
http://www.bxclub.co.uk/forum/viewtopic ... 15&t=17847" onclick="window.open(this.href);return false;

-after replacement of the orgiginal element against overload (which contacts were only realized by pressing) by an ptc thermo switch with was solderd to the pcb, there was no difference in power to realise, which may be worth to do this mod.

- so if you realise a bigger difference, check the contacts of the element for overload protection.

nevertheless there is an advantage of this mod: the transistor produces no more heat at full power. in this way the risk of its distruction is reduced strikingly.
User avatar
Des Smith
1K Away
Posts: 1178
Joined: Sun Apr 03, 2011 10:17 am
Location: Sydenham, London
x 2

Re: The definitive heater modification

Post by Des Smith »

Just to report my fan stopped working, intermittently at first, then permanently. Demisting has therefore been no fun this winter, to the point that I finally had enough and plucked up courage to take the panel off and do the mod. It all went as per the thread instructions, but when I tested it, nothing. I then tried bridging the pins as described and bingo, a veritable gale! So I've soldered a bridge between pins 3 and 4 and re-assembled and normal service has been resumed. In hindsight, a dodgy earth would explain the intermittency.

When I looked at the panel bulbs, they had both blown, so now I just need to get hold of replacements and it will be dead simple to take the panel off and pop them into the holder.

:D :D :D
BX14TE St Tropez 1990 - now sold
Xsara Forte 1.4i 2000
Kawasaki GPz550A4 1987
User avatar
David
BXpert
Posts: 529
Joined: Sun Oct 27, 2013 10:54 pm
Location: Manchester
x 47

Re: The definitive heater modification

Post by David »

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.
1992 Citroën BX 1.9 Diesel Meteor 4x4 - The Project.

1992 Citroën BX 1.9 TXD (with GTI engine; Mulleys old car) - Parts car.

2004 Citroën Xsara Desire. (Now gone).

2016 Ford Focus Zetec - Daily Driver. (Absolute bone shaker).
User avatar
Des Smith
1K Away
Posts: 1178
Joined: Sun Apr 03, 2011 10:17 am
Location: Sydenham, London
x 2

Re: The definitive heater modification

Post by Des Smith »

David wrote:Last time I had the dash out of my car...
Last time? How many times have you had the dash out?! Respect to you! Thanks for the steer, but somehow I think I'll need a very big incentive before I pull out the dash to look for a dodgy earth.
BX14TE St Tropez 1990 - now sold
Xsara Forte 1.4i 2000
Kawasaki GPz550A4 1987
Defender110
Over 2k
Posts: 5918
Joined: Wed Dec 16, 2009 8:02 pm
Location: Harwood, Bolton
My Cars: Land Rover Discovery Series 1 200tdi 3 door
Land Rover Discovery Series 2 Facelift TD5
2020 Fiat Panda cross 4x4 twin air.
x 27

Re: The definitive heater modification

Post by Defender110 »

Well done David, I wondered where it went to.
Kevan
1997 Mercedes C230 W202
2003 Land Rover Discovery Series 2 Facelift TD5 - Daily driver / hobby days and camping.
1993 Land Rover Discovery 200tdi Series 1 3 door - in need of TLC
2020 Fiat Panda 4x4 Cross Twin Air.
citronut
Over 2k
Posts: 2781
Joined: Wed Oct 31, 2007 7:55 am
Location: EAST SUSSEX UK
x 1

Re: The definitive heater modification

Post by citronut »

Des Smith wrote: just need to get hold of replacements
try the likes of

http://tinyurl.com/new62w9

regards malcolm
curent ride
K reg BX 17TD TZD est
also own
K reg D special

no longer have
H reg CX saffari 2.5 TRI (now gone to Malaysia)
R reg xantia 1.9TD est (gone to meet its maker)
User avatar
Des Smith
1K Away
Posts: 1178
Joined: Sun Apr 03, 2011 10:17 am
Location: Sydenham, London
x 2

Re: The definitive heater modification

Post by Des Smith »

Hmm. Bit pricey. Just been down the local motor factors. 20p each, so I bought a few as spares. :D
BX14TE St Tropez 1990 - now sold
Xsara Forte 1.4i 2000
Kawasaki GPz550A4 1987
User avatar
Way2go
Over 2k
Posts: 7279
Joined: Fri Jan 13, 2006 3:15 pm
Location: RCoBerkshire
x 2

Re: The definitive heater modification

Post by Way2go »

Des Smith wrote:Hmm. Bit pricey. Just been down the local motor factors. 20p each, so I bought a few as spares. :D
:? How come? 17p is better than 20p. Still, you managed to buy quickly & fix. :-D
1991 BX19GTi Auto