BX heater fan max speed relay - WHERE ?

AndersDK · Post by **AndersDK** » 16 Mar 2004, 04:51

Blower noise issue (full speed) ??
Reliability issue - i.e. blower/harness not taking the full power for long ??
Hmmmm.... will definately try tomorrow if full speed setting on the knob resembles a direct battery feed to blower - as I think mine's a bit lean on air - even though everything seems to work - and motor brushes replaced last summer.
There should be a vague - but still distinct - click from the max speed relay - noticeable with engine off & ignition on.
This is a DK imported '89 BX16
Interesting issue fellas....

DLM · Post by **DLM** » 16 Mar 2004, 05:06

Well, my relay currently goes clickety-click if you pull/push the control knob. I realised this might be a result of missing screws on the panel from when I reclipped one of the wires. Curiouser and curiouser.

oilyspanner · Post by **oilyspanner** » 16 Mar 2004, 12:22

Jack Dempsey, didnt get an email from you? I currently have the same problem so if you find the relay perhaps you could draw me a map of where to locate the thing, I actually have two fan cards in stock at the moment.
Stewart

jack.dempsey · Post by **jack.dempsey** » 17 Mar 2004, 18:04

Oilyspanner - the relay is located on the right hand steering wheel support bracket on my TZD. Interestingly I've studied my original speed control PCB and come to the conclusion that it would not energise this relay under any condition (it does NOT agree with circuit diagram in Haynes manual). I have received a replacement from a scrappy that has a PCB of a diferent design to my original. My original had a carbon track printed directly on the PCB, rather like a potentiometer, and the wiper bears directly on this (and wears it out over the years). The replacement however has a different wiper (sort of three fingers) which actual bear on to radiating metallic tracks which connect, under some semi transparent protective plastic cover (not found on my original pcb), to the resistive compound. This replacement pcb does cause the relay to energise at 'full' speed - which obviously bypasses the variable control elements of the 'volume' control and stops it burning out (like what mine did). I did remove the full speed relay from the steering bracket and teased the works out of the fairly small box. The contacts were as new - no signs of pitting or burning what-so-ever. I doubt that this relay has ever switched in the cars life. Now to glue it back together and refit to steering bracket (everything is currently hanging out under the dash!). Pity that my replacement control unit (fan housing) didn't work (fan runs about half speed all the time - except when relay operates to make it run at full speed). The scrappy is sending me another one. If that also fails I may be in the market for a 'new' one.

jack.dempsey · Post by **jack.dempsey** » 17 Mar 2004, 18:13

Tomsheppard - yes the picture on your web site is identical to my original PCB - and I agree, after pondering long and hard at both the PCB and Mr Haynes wiring diagram, I too have concluded that its just 'not wired up right'.
I'm so relieved that you have confirmed this as I was starting to get paranoid about it - I mean who really cares if the high speed relay works or not - it hasn't for 14 years, so long as the fan 'goes' and can be controlled. I've been reminded of this 'view' several times over the last couple of weeks by 'her indoors'.

tomsheppard · Post by **tomsheppard** » 17 Mar 2004, 18:54

Try the mod Jack. You'll thank me for it come summer.

AndersDK · Post by **AndersDK** » 17 Mar 2004, 21:45

strange -
My '89 BX16 blower max speed relay defo does'nt come on - and there is no "dead" setting on the control knob.
Then I have the same "wrong" circuit board as you guys talks about ...
Fiddling time then [8)]

tomsheppard · Post by **tomsheppard** » 17 Mar 2004, 22:05

Ok so now we're all agreed on it. Here is the definitive how to:
First: cut the very thin vertical track in the bottom right hand corner of the PCB. Second: solder a piece of wire between the two ends where there is an obvious gap in the track. That is all you need to do. You may not need to remove the board if your soldering iron has a long enough lead. Takes no more than ten minutes.

AndersDK · Post by **AndersDK** » 18 Mar 2004, 00:00

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by tomsheppard</i>

You may not need to remove the board if your soldering iron has a long enough lead. Takes no more than ten minutes.
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
[8D] Tom [8D]
- does this in fact mean the board is left in place in control panel - just removing the knobs and under-knobs-facia piece ?

jack.dempsey · Post by **jack.dempsey** » 18 Mar 2004, 00:34

I think it is possible to do it in situ - just make sure you've got the PCB as shown on Tom Sheppards web site. You'll know I suppose 'cos the type that I've now got triggers the relay as it supposed to. Dashboard almost back together now - just the heater fan and housing to re-attach under the top grill on the outside (tomorrows job).

tomsheppard · Post by **tomsheppard** » 18 Mar 2004, 14:02

Yes, the board may be left in place.

DLM · Post by **DLM** » 18 Mar 2004, 20:02

Just for reference,and to round off the thread, the relay is mounted on the base of the steering column bracket, very low and to the right-hand side (from observation on an '88 rhd car on which the relay WAS working). I'd have taken a photo but didn't have the camera to hand.
You may find it "easiest" to see by looking upwards from a point somewhere near the pedals - so long as you're able to get your head into the footwell area of a BX without causing injury or distress!
Alternatively, you can remove the choke/mirror/foglight switch panel and peer in from there.

jack.dempsey · Post by **jack.dempsey** » 19 Mar 2004, 03:08

This subject now continued in thread "go faster fan mod" - see you there.

mikeg · Post by **mikeg** » 16 Aug 2004, 16:14

Is it likely this mod could cure the problem on one of my BXes ?
Nothing happens until I select max fan speed, then the fan starts to trickle over as if position 1 has been selected. If I do this with the radio on AM I cannot hear the fan switch on until it actually reaches max. Wots think lads, or any other ideas please.

jack.dempsey · Post by **jack.dempsey** » 17 Aug 2004, 18:22

Mikeg - this fault you describe is almost certainly the electronic unit in the ducting near top the fan. Carrying out the modification to the control would give you max speed when selected full on - but electronic unit is really responsible for controlling the speed. This is exactly how my original post started - and was fixed with a new speed control unit. Im saw one on ebay recently for a few quid (306 unit is the same I think) - but expect to pay around 40-50 quid for a dealer part.