More Heater blower problems

[peter306]

Xantia 1.8 2000 year

Car hadn't been used for a couple of weeks. needed a new battery.
Blower didn't work on restart.
I've been through the instructions on Rory Perretts post.
The motor runs with a direct feed.
There is 12 volts at the brown plug no voltage at the two leads to the motor.
There is 12 volts at the orange wire, no change when the slider is moved.
engine on they become 14 volts.
put the fan back on the motor, started the engine and using a thin bit of wood slid it under the heatsink and pushed the relay,
The fan started
Conclusion, either the slider or the resistor pack.
Can the resistor pack be checked for faults.

Peter

[mickthemaverick]

You may find this video helpful

[peter306]

Mick, thanks for that but its the one mounted on the blower motor casing with 2 darlington transistors, can those transistors be tested/checked

peter

[CitroJim]

Mick, thanks for that but its the one mounted on the blower motor casing with 2 darlington transistors, can those transistors be tested/checked

peter

Hi Peter, I've been all over this topic like a rash... If there's no change of voltage on the orange wire then either there's a in the blower speed regulator pulling the control line high or there's a problem in the aircon ECU. Check the voltage vs. slider position on the orange wire with the speed regulator disconnected.

The usual fault with the blower module is emitter - collector shorts in one or other of the pass transistors causing the blower to run uncontrollably at top speed.

I still have a few pairs of replacement transistors here...

This old thread has some valuable information

https://frenchcarforum.co.uk/forum/view ... hp?t=24786

[peter306]

Hello Jim,
Been through all that, even printed off Rory Perretts post and sat in the car going through that.
a couple of things I may have done wrong.
I assume I should have checked the orange wire with the brown 4 pin plug disconnected from the motor.
On the ECU there are two thicker wires, the blue one has 12 volts, what does the pink one next to it do,
the pink wire has continuity with fuse 6 and 21.

[CitroJim]

what does the pink one next to it do,
the pink wire has continuity with fuse 6 and 21.

As far as I recall it's a connection to a thermistor to provide a bit of feedback to compensate for speed changes that would occur as the darlington transistors change temperature..

[peter306]

Finally got around to checking the wiring on the 4 pin blower motor plug with the plug removed, as Jims instructions.
12 volts between black and red wires, engine off, just over 14 volts engine running.
the orange wire as hardly any voltage on it, just over 1 volt checked between the wire and earth, and it doesn't change with slider movement.
I then checked the wires on the slider control, 5 wires checked between the 5 pin socket and earth, voltages between 1.5 and 4, no change with the slider movement.
Also put the lexia on it and just like at Alasdairs it didn't connect to the aircon ecu. Apart from that no faults.
So I think either the speed control module or the aircon ECU.
My VIN is VF7**************[VIN obfuscated, can be read by forum staff]
Can someone tell me the correct part no for these for my car, the paper labels are unreadable and there are a few different ones out there.

Thanks Peter

[CitroJim]

So I think either the speed control module or the aircon ECU.
My VIN is VF7**************[VIN obfuscated, can be read by forum staff]**************[VIN obfuscated, can be read by forum staff]
Can someone tell me the correct part no for these for my car, the paper labels are unreadable and there are a few different ones out there.

Thanks Peter

Be careful with the blower regulators Peter, there's a few dodgy fakes out there..

I've see one with NPN darlingtons rather than the correct PNP pair... Needless to say, it didn't work.

You'll be far better off trying to source good used items... Duff blower regulators are easy to fix. The Aircon ECU drives the darlingtons directly and all the electronics does on the board is operate the full-speed relay.

If the Aircon ECU is duff, that may be an easy fix too... The fault is likely just the darlington driver transistor gone short...

[peter306]

Hello Jim,
You said you've got some transistors spare, how much to send some( say 4).
I've looked at the regulators online,they either have different transistors or no markings on them.

Peter

[CitroJim]

If the blower is NOT running uncontrollably at top speed Peter, it's very unlikely to be the transistors. If, with the speed regulator disconnected, the control line going to it does not change with the position of the slider, then the problem is more likely in the aircon ECU.

[CitroJim]

Also, I believe Chris570 may have what you need. He took all of my remaining Xantia spares and I believe that might have included a pile of regulators...

Have a chat with Chris here via his post:

viewtopic.php?t=86734

[peter306]

so I took the cover of the aircon box.
Does the fact that one of these is a different colour mean anything.

Peter

[CitroJim]

so I took the cover of the aircon box.
Does the fact that one of these is a different colour mean anything.

Peter

Potentially, yes it does. It depends upon what line it's on. Does it trace through to the Blower Regulator speed control line?

[peter306]

Hello Jim,
The fact that it's different exhausted my knowledge on this
How do I check where it goes to, I have visually traced it to a hole about an inch down.

Peter

[CitroJim]

Hello Jim,
The fact that it's different exhausted my knowledge on this
How do I check where it goes to, I have visually traced it to a hole about an inch down.

Peter

We need the full wiring diagrams Peter... I'll see what I can do. I may still have them reasonably available... I'll have a look when I can... It may be a while as I'm currently up to my ears in many diverse happenings currently