Climate control sensor and fan

Clogzz · Unread post by **Clogzz** » 16 Jul 2007, 13:44

First map, item B37, in-car temperature sensor, pins 1 & 2 for the sensor.
The electronic motor drive, pins 3 & 4.
Last map, top right, sonde température habitacle ventilé.

MikeT · Unread post by **MikeT** » 16 Jul 2007, 16:09

Thanks for that Clogzz though I've failed to make myself clear again, sorry.

The motor isn't directly powered by pins 3 & 4, they go into a small pcb mounted on the base of the motor.

Do brushless motors require a controller or can voltage be applied as per a brush motor?

Is this pcb a generic brushless motor controller or is it an add-on which can be bypassed? I assumed the latter but that's because I don't fully understand brushless motors feed requirements.

The motor itself has four terminal legs and these are soldered to the pcb. If I can apply voltage directly, which of the four do I use?

RichG · Unread post by **RichG** » 16 Jul 2007, 18:53

Mike,

Try this http://en.wikipedia.org/wiki/Brushless_ ... tric_motor for the theory.

Richard

MikeT · Unread post by **MikeT** » 16 Jul 2007, 19:27

Hi Richard,

I had to read it twice and it seems they do utilise a controller - I'm not clever enough to understand the logic of it all though.

Presuming the controller is integral to the motor, I'm hoping I can source a direct replacement brushless motor.

If it's a non-standard motor, I'll see if I can bodge something small to fit in it's place.

AndersDK · Unread post by **AndersDK** » 16 Jul 2007, 23:51

Mike -

Before you dig too deep into this issue - call Citroen and ask for a spare parts price tag.

next : brushless DC motors are the only fan motors used in PC's & homecomputer equipment.
Try any computer dealer for a 12V cabinet blower. They come as maxiblowers, silent blowers and flash my ride (blinking LEDs while running) types.
Be sure to get a 12V type - not a 5V type.
You will defo want a silent blower of the smallest 12V type.

Third : there is no elctronic control for the brushless DC fan motors. Its build in behind the blower blade rotor. What you see on the PCB is the temp sensor itself, and possibly a couple of radio interference decoupling capacitors.
With some fiddling it should be easy to move the pcb over to to new blower. Be prepared though that you must power up your soldering iron

You can get a long way with nylon strips zipping the bits together. The sensor does not have to be perfectly in the middle of the blower stream.

Clogzz · Unread post by **Clogzz** » 17 Jul 2007, 13:13

there is no electronic control for the brushless DC fan motors

Wondering what that transistor symbol going to the motor does ?

The blower motor shows that too.

MikeT · Unread post by **MikeT** » 17 Jul 2007, 13:45

AndersDK wrote:Mike -

Before you dig too deep into this issue - call Citroen and ask for a spare parts price tag.

Citroen are asking £Too much

Third : there is no elctronic control for the brushless DC fan motors. Its build in behind the blower blade rotor.

Sounds like a contradiction for my simple mind - is there or isn't there an electronic controller required for brushless motors?

What you see on the PCB is the temp sensor itself, and possibly a couple of radio interference decoupling capacitors.

Yes, 3 caps, one resistor and a sprinkling of surface-mount components but the power (+12V & -12V) for the motor passes through this circuit (as well as the temp sensor) and becomes four outputs to the motor windings.

With some fiddling it should be easy to move the pcb over to to new blower. Be prepared though that you must power up your soldering iron

Desoldered and waiting 8)

Clogzz · Unread post by **Clogzz** » 17 Jul 2007, 14:03

That’ll be waiting for Anders

to be back.
Until then, there’s RichardW’s explanantion:

RichardW wrote: it seems to use some sort of modulated signal to make it run (presumably to keep it quiet) and what seems to happen is that the electronics give up which causes the fan only to kick when switched on and not run.

A motor for this function would normally not need an electronic drive, because it always runs at the one full speed.

MikeT · Unread post by **MikeT** » 17 Jul 2007, 14:31

I read Richard's post earlier which got me thinking I could re-use the motor, bypassing the electronics, if I can figure out where to apply the power direct to the motor.

Clogzz · Unread post by **Clogzz** » 17 Jul 2007, 15:08

The motor itself having 4 terminals, is it not 2 terminals being the earthing of the metal case ?
Pins 3 & 4 would go to the winding, and right or wrong are spinning one way or the other.
Back tomorrow.

AndersDK · Unread post by **AndersDK** » 17 Jul 2007, 16:00

Things are mixed up here.

To clarify :
Yes - a brushless motor needs electronics to run off a DCvoltage.
No - the standard commercial available computer blower fans needs NO external electronics.
The necessary electronic circuit is built into the fan itself. Thats why it has a relative large mid-section. That midsection is NOT only the bearing - but a tiny PCB with some transistors etc.
You will instantly recon if you break the old fan apart.
(you will find a tiny axle C-lock ring under the paper label on the fan)

Now for the Xantia genuine blower circuit : I recon from Clogzz's kindly submitted schematics, that appearently there is some kind of external electronics circuit for the sensor blower fan.
However that can only be some kind of a voltage regulator, presumely a switcher or a square wave pulser, to omit any serial power loss (heat) from a standard linear voltage regulator. That would instantly upset the temp sensor readings

It also explains the "interference" capacitors, as pulsed voltage is a source of radio interference.
Conclusion is then, that the external electronics circuit is there to lower the drive voltage for the fan, to make it run slower, more silent and last much longer.
That is valid for the temp sensor blower fan ONLY

On the other fan circuit its noted that this is the "ventilateur chauffage" i.e. the cabin heater blower - on which we want to set the speed by choise.
So thats why its shown with a different kind of electronics circuit & more connections. These connections go to either the computer for automatic climate control, the ventilation panel knob control settings - or both.

Hope this is some light in the dark

NOTE : please do not reverse the fan voltage, some cheaper types dont even have a series protective diode built in

MikeT · Unread post by **MikeT** » 17 Jul 2007, 18:15

AndersDK wrote:Things are mixed up here.

To clarify :
Yes - a brushless motor needs electronics to run off a DCvoltage.

Ok.

The necessary electronic circuit is built into the fan itself. Thats why it has a relative large mid-section. That midsection is NOT only the bearing - but a tiny PCB with some transistors etc.
You will instantly recon if you break the old fan apart.
(you will find a tiny axle C-lock ring under the paper label on the fan)

Looking at the parts I have, I can't see any circuitry in the motor at all

This is a picture of the assembly consisting of a two-piece plastic housing. The plug wires going through the smaller housing (red, black & 2 grey) are soldered direct to the pcb. A thin connector strip carrying the temp sensor wires go left into the larger housing and connect to the thyristor (just out of shot) on a strip board.

The motor is soldered to the pcb via four pins at each corner. This is it desoldered and the rotor removed.

Inside the motor we can't see any electronics.....

AndersDK · Unread post by **AndersDK** » 17 Jul 2007, 18:31

Now I'm really confused

On the schematic from Clogzz its shown to be only 2 wires running to the electronics - and from the electronics on to the motor - still only 2 wires.
On the schematic it only shows a DC motor running off a constan supply AND the sensor with one wire connected (other side of sensor is grounded via a mounting screw - MUST be)
For the temperature sensor blower motor
Is that really the small buzzing temp sensor motor off the airduct you've got there Mike ?

If so - then I'm completely off track now - as I was convinced it was the type found in computer equipment.

AndersDK · Unread post by **AndersDK** » 17 Jul 2007, 18:47

Ahhh ...

Wait a minute.
There are 2 wires for the motor - and 2 wires for the sensor. As this is apparently a later modified type with no chassis fixing screw. There is absolutely no electronics involved in this variant either - despite the schematic.
The motor is a fairly standard DC motor, no electronics needed.

The sensor would be that "dingy" located separately on the small long strip of PCB, because thats where the airstrem comes from the running motor.

So what you need is still a small standard DC brushless motor as found in PC's. You simply connect a series resistor in series with the one motor lead then, to bring down motor speed and noise.
Be sure the resistor is out of the way of the airstream past the sensor, as it may influence the sensor reading.
You will need a 33 ohms resistor in series I think to bring down the motor speed. If the motor wont run, you must choose a lower ohmic resistor (27 or 22 ohms). If the motor howver still runs noisy you need a higher ohmic resistor (47 or 56 ohms). Resistors must be at least 1watt rated. Only a few pence each in Radio Shacks or Maplins

MikeT · Unread post by **MikeT** » 17 Jul 2007, 19:18

Well getting back to my original query (it was suggested the pcb has failed), can I test the motor seperate from the pcb? If so, how?

I'm beginning to think there's more to this pcb than just noise or interference suppression....