Blowers - C4 Grand Picasso 2010 (60) Auto Diesel

[dand777]

Hi - I’ve seen that a couple of people on the forum have had a similar but not quite the same issue as me, and the relevant threads are quite old, so I hope nobody minds me asking this question:

Problem - heater blower fan not working. Control panel lights up and the buttons affect the shown setting, I can hear the directionals changing, just no movement from the fan.

Here’s what I’ve tried so far. Please be aware that I am neither a mechanic nor a leccy, just a have-a-go-er.

Checked all the fuses I could find listed as relevant on the net, and they seem fine. My understanding is that if they were gone there’d be no light to the panel? If this is wrong can anyone help tell me which ones may need attention?

Removed the fan and resistor from under the dash above the pedals. Replaced with new parts and gave all connections a good clean. Still the same.

Got hold of a voltmeter and tested the current coming into the power plug of the fan, and here’s where my issue is slightly different… I was getting current but as far as I can tell from the VM it’s only 4.7v at full fan setting, and is affected downward when I turn the fan down using the control. Is that the issue? Most posts I’ve seen tell me to expect 12-14v supply here. If so, which part is causing the problem?

Just in case it was the relay, I sourced a new one and replaced the only similar looking relay I could see in the engine fuse box above the battery… No difference.

Can anyone offer any guidance as to anything I might have missed, done wrong, or next steps?

Thanks in advance.

Dan

[GiveMeABreak]

Dan, did you actually change the Blower Motor Control Module? The reason I ask is that some people get this mixed up with the Cabin Air Heating Resistance.

If you replaced the correct unit, then also be aware that cheap aftermarket units are notoriously bad for being dead on arrival or just not working. Make sure you get a decent branded one, either Citroen or a BEHR / Valeo / Febi brand or similar. Avoid Chinese rubbish.

[dand777]

Thanks for the quick response Marc - already you’ve hit the limit of my knowledge!

So the replacement parts I have tried are:
Blower motor and fan - replacement from EU Autoparts, new
Resistor (that bolts on to the side of the motor) - new from eBay, brand described as “OE quality”.

Relay - used

I guess there’s a chance that some of those could be DOA. If I could apply voltage direct to the fan and resistor from the battery and it runs, that would confirm them as not being duds right?

The blower control module you mention here - is that a different part?

[GiveMeABreak]

Can you pop up the VIN of the vehicle (automasked on post submission for your protection) so I can see which system you have.

[dand777]

Of course - it’s VF7**************[VIN obfuscated, can be read by forum staff]

[GiveMeABreak]

Ok, so this is the arc shaped unit that can be separate or mounted on the blower motor.

I've taken a look at the wiring diagram and just to make sure you checked the correct relay.

8048 on the wiring diagram below is the Relay for the Blower Control Module (which is the Arc-shaped resistor on the blower fan motor itself).

This relay in turn is supplied by the Maxi Fuse (MF8) under the engine Fuse Box.



Here is where it is located on the vehicle - (8048):

[dand777]

Yep so the arc shaped unit is what I’ve called the resistor above and has been replaced with new.

I was checking the right relay, it’s the one attached to the inside of the engine fusebox by a little spring-clip.

Am I right in thinking that if the maxi-fuse had gone I’d have a lot more problems than the blower not working?

Also, do you think there’s anything in my discovery that only 4.7v was being output by the blower controls on max? Can you think what might be causing that, and could it explain my issue?

What to try next?

[GiveMeABreak]

I've only dealt directly with the C5 versions which have a completely different system. I have dug this out though and as you can see, 5V is about right for supply to the control module as shown below.

Fan speeds are controlled using the control module, the air conditioning control panel on the driver's side 8021 (CH and RF), or the system computer air conditioning 8080 (RFTA and RFTA GA). The command is a voltage signal depending on the set fan speed.
The signal received between terminal 1 of the control module and ground for various fan speeds.

"A" Engine is stopped.
"B" Fan at eighth speed.
Each voltage level corresponds to one fan speed (from 0 to 8). Terminal designation of the control module:
Terminal 1: Control signal from the air conditioning computer (8080)
Terminal 2: 5V power supply to the control module (8045)
Terminal 3: Ground
Terminal 5: Power to the fan motor (8050)
Terminal 6: Switching on the mass of the electric fan drive (8050)