Heater/Fan sliding control

Pathfinder100 · 2025-03-03 18:35:02

So from what i'm seeing the heater control is a single unit and the avg price is £70. Needless to say I have no interest in paying £70, since only the on/off slider is broken. Is it possible to bypass the slider and use a variable switch, like a variable resistor type fan control switch, ie, a £5 part? If it ran all the time at minimum or didn't switch off i'd be ok with that, or if it ran at full all the time and had to be put on a rocker switch.

https://www.ebay.co.uk/itm/156712277435 … ter+switch

@kenbw2, Do you by any chance have any pics of how your rotational knob switch is wired up to the fan, as highlighted in this (old) thread?

https://dispatchexpertscudo.org.uk/foru … 4256#p4256

Last edited by Pathfinder100 (2025-03-03 18:55:47)

kenbw2 · 2025-03-03 21:34:22

Pathfinder100 wrote:

@kenbw2, Do you by any chance have any pics of how your rotational knob switch is wired up to the fan, as highlighted in this (old) thread?
https://dispatchexpertscudo.org.uk/foru … 4256#p4256

I was about to find that picture! Sadly not - that control came with the (old, no longer with me) van and I never dismantled it.

It should be straightforward though. Assumedly behind the slider there's one wire in, one wire out. Can you just steal from those and put them on the variable resistor?

RegW · 2025-03-04 14:55:05

From the diagrams I've found, the slider just sends a variable voltage to the Driver
circuit mounted on/near the fan motor housing
This is where the power is controlled to dictate fan speed
If the diagrams I have are to be trusted it controls the ground path current.

I haven't looked at mine so can only make guesses and assumptions
but would probably start by checking the signal voltage
to the controller on what my diagram says is green wire.

If I got no voltage I'd suspect the slider which would be relatively easy to hack
or workaround with an external potentiometer.
If I got a varying voltage, I'd suspect the controller which I can only guess is either a PWM device or maybe just a simple power amp
The motor itself may be knackered for all we know so a temporary direct control hack would help decide what action to take next.

Pathfinder100 · 2025-03-04 15:03:37

I've been trying to work out in my mind what could have caused this. Last night I pulled in at Tesco and the second I pulled on the handbrake, the fan fired up and just ran until i switched the engine off. When i restarted it after shopping it fired up for a bit until I took the handbrake off. This all started when i went looking for that alarm box I found under the steering column. The clock on the instrument panel is running slow, where as before I did everything it was fine. There was a wire in the back of the radio held in by a screw. Since the radio lost it's code and doesn't work I just took that wire and taped it.

I'm wondering if the alarm box removal, that wire or the fact i didn't reconnect the radio has caused this issue. If the control is on the ground current and the ground was dodgy and one of those components was creating an alternative ground in the circuit, would that account for why my blower has glitched and the clock runs slow? No idea, but i'm going to try plugging the radio in, then maybe try plugging the alarm back in. See if it makes any difference.

After that i'll have another go at removing the dash and see if I can work out what isn't working and maybe bypass the power to the fan if needs be and run it from somewhere else.

Thanks Reg.

Last edited by Pathfinder100 (2025-03-04 15:06:07)

RegW · 2025-03-04 15:57:45

did you try to see if you had any control over the fan speed before switching off
or were you target fixated on retail therapy? devil

It does sound as if you have erratic connections or grounding issues though

As we have what appears to be the same model/engine
I'd be interested in the alarm removal process as I have an alarm on mine which is non functional
and Id like to remove it in case it causes problems

Pathfinder100 · 2025-03-04 16:37:21

It does work/change if I slide it, but then it drops out. It's happened a few times now. I can replicate it sometimes by reversing into a space and then putting the handbrake on, but it seems to be getting less likely to trigger when I do that.

The alarm box removal wasn't hard or complicated. As I remember I just pulled the connector out of the back and clipped the cable tie holding it in place. Mine was going off, sounding the horn and flashing the indicators when the battery got low and it was cold. It also didn't work aside from that. I suspect it might have been tied to the key remote central locking that doesn't work because the coded key has been removed from the van ecu at a guess (it starts on a generic unchipped key).

I'm currently wondering whether to create a new grounding point, wire it into a busbar and then connect it to the back of the internal fuse board. So it has a stable ground. but first i'm going to reconnect the radio, get the instrument console back out and see if I did something stupid back there or see if there's any loose or random wires I can see. Failing all else, find the grounds coming out of that alarm connector, radio, instrument console and connect them to a new grounding point on the chassis. Since when applying the brake, the only light that comes on is the one on then instrument console, my guess is the grounding issue is between there and the heater.

Pathfinder100 · 2025-03-07 04:56:36

And without doing anything, it has started working again, all the time. neutral

So i'm convinced it's a grounding issue. I'm going to grab one of those prebuilt battery leads they sell at Halfords and make a new chassis ground point somewhere near the battery and connect it to it. Then at least one decent ground will exist for the vehicle.

Last edited by Pathfinder100 (2025-03-07 04:57:06)

RegW · 2025-03-07 15:49:44

I'd suggest you check and clean the existing ones
IMO Its rarely the cables but the terminals that go bad
Diagrams show these vans have various searth/ground points
The main one near the battery another just in front behind the headlight
One on the driver side near the ECU
in the cab there are points under the dash either side with 2 near the heater motor and fuse box and this is where the heater motor and it controllers get a ground.

A can of contact//switch cleaner and squishing it into any connectors you come across will do no harm either

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#1 2025-03-03 18:35:02

Heater/Fan sliding control

#2 2025-03-03 21:34:22

Re: Heater/Fan sliding control

#3 2025-03-04 14:55:05

Re: Heater/Fan sliding control

#4 2025-03-04 15:03:37

Re: Heater/Fan sliding control

#5 2025-03-04 15:57:45

Re: Heater/Fan sliding control

#6 2025-03-04 16:37:21

Re: Heater/Fan sliding control

#7 2025-03-07 04:56:36

Re: Heater/Fan sliding control

#8 2025-03-07 15:49:44

Re: Heater/Fan sliding control

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