Not another Heater blower not working post

[Jimmy8157]

Afternoon all

So after scouring through all the posts on heater blower issues on the forum (there are many) I'm not able to solve the problem I'm having.

So I have a Citroen c4 GP 2008 (58 plate) vin is VF7**************[VIN obfuscated, can be read by forum staff] and my heater blower has stopped blowing, at first I thought it was a fuse ..all fuses seem ok. I went straight to the blower and noticed that my wiring on the resistor unit had burnt out and melted. I repaired the wiring (however the clips are destroyed. the yellow connector plug is ok (I only get about 5v there not sure if that is correct) and I get 0v everywhere else. I'm guessing the plug from the main harness is the 12v feed coming into the resistor unit?

I've checked all relays and fuses and I'm just not getting any power to the big wires coming into that resistor unit.

Does anybody have any ideas? Any methods I could use to check?

I've had the blower apart and all seems fine and free. I've had the resistor off and doesn't seem to bad.

I'm thinking I'll buy a resistor unit then see how it goes but still I don't know why it's not getting power, unless I'm missing something?

Thanks guys

[Dormouse]

Did you check for continuty across the heater connections or clean them all up?

[Sloppysod]

No sure, if this helps, but had issues with my wife's Corsa heater blower over the last 10 months or so.
I replaced the heater resistor, worked fine 8 months (Summer) then it packed up again, I replaced just the thermal fuse, and it went again after a few months. Further 'tinkering' proved that from cold the motor was not getting enough power to start, but if I turned to position 3 then down to speed 2 it would work fine, but not for speed 1!
The conclusion was that the motor was starting to sieze. New motor fixed it

As I said this was for a Corsa, but I would imagine they are all similar, basically, lower voltage means lower speed.

[Jimmy8157]

Did you check for continuty across the heater connections or clean them all up?

The heater seems fine ...just the resistor connections needed cleaning as they were burnt and melted.

My question is, does the 12v feed come in from the harness to the resistor unit?

[Jimmy8157]

No sure, if this helps, but had issues with my wife's Corsa heater blower over the last 10 months or so.
I replaced the heater resistor, worked fine 8 months (Summer) then it packed up again, I replaced just the thermal fuse, and it went again after a few months. Further 'tinkering' proved that from cold the motor was not getting enough power to start, but if I turned to position 3 then down to speed 2 it would work fine, but not for speed 1!
The conclusion was that the motor was starting to sieze. New motor fixed it

As I said this was for a Corsa, but I would imagine they are all similar, basically, lower voltage means lower speed.

With mine I thought it was the resistor unit... But I'm not getting any feed into that so I'm guessing/ trying to find the feed.

I thought it would be into the resistor unit but I can't find any decent wiring diagrams anywhere. I have 12.8v (not running) so I know the battery is good

[GiveMeABreak]

Here's the wiring diagram. Note that there is a relay that directly controls the blower control module (8045) located below where I have circled in Blue, where the fuses are under the bonnet.

Here's the main diagram:



8045: blower control module (if separate)
8023: passenger´s aircon control panel
8048: the blower relay (see my picture above for location)
8050: blower motor (if separate)

[Jimmy8157]

Thanks for all that Marc, if relay 8048 is the relay by itself just Infront of the engine bay fuse box, then I've checked that one and seems all ok, however I can do a proper diagnosis tomorrow now that I have that diagram.

Looking at that diagram (if the circuit was working currently) I should have 2V at wires 8020 / mc46h? Or have I read that wrong?

Thanks for all the help from you and the forum so far

[GiveMeABreak]

No, 2V NR means a 2 pin black connector (it's French).

So in the diagram 8045 is the blower control module and this has 3 x 2 pin black connections.

On that module the wiring shown on each of the 2-pin connectors is:

8018 : blower control module requirement
8019 : blower control module diagnosis

A2 : accessory +ve
A1 : accessory +ve

8020 : air conditioning motor control
MC46H : earth mc46