C4 heater/air con not working

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Hoppykat
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Re: C4 heater/air con not working

Post by Hoppykat »

I’m having the same issue, tested wires and getting 14v with engine running , when plugged into heater unit I’m getting 1.8v , replaced the resistor and fan but still not working , mines a c4 grand , looking at bridging the wires idea but not a clue which wires? Any help would be much appreciated :-D
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Re: C4 heater/air con not working

Post by Marcol »

I'm having the same issue on a Peugeot 308 which im led to believe is the same system.
Checked the motor with 12v, not the problem,
Ordered a replacement resistor, didn't fix it.
Just tried splicing and bridging the 2 wires in the fuse box(without a fuse), still didn't work.
Any thoughts on where to check next?
Should mention it's a dual zone auto system.
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Re: C4 heater/air con not working

Post by Arthuros-+ »

Hi , i have the same problem , the blower not working ,it is dual zone ac 2008. Have replaced the fusebox but still no power to the unit. Have applied 12v direct and fan is working. The display is iluminated and al buttons are working. Before puchasing the fusebox SH on eBay have tried bridging the two wireless to bypass the relay but no joy. Weather is now wet and have loads of condensation on widscreen. Please someone help!
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Re: C4 heater/air con not working

Post by GiveMeABreak »

It's been well-discussed on various threads here.

Water condensation can get into and start to rust the motor bearings. Models with automatic climate control systems tend to 'step' the blower motor from a low speed at start up and gradually increase as needed to get the desired temperature as efficiently as possible. Often if the bearings are starting to or have seized in the blower motor, there is insufficient power to get the motor going. This is where the temporary bypass of shunting to full power can sometimes kick start the blower motor. It will depend on how seized the bearings are I suspect - and at some point they just won't move - and this is where you risk damage / danger of overheating if you are bypassing the fuse.

Testing the Blower Motor Control Module by temporarily bypassing it will determine if the module is at fault and needs replacing - but if there is current to the motor directly and it still doesn't operate then it's likely your Blower motor needs changing. Also at this point it is worth bearing in mind that some vehicles and models have the blower control motor module built onto the blower motor, so is not a separate module.

For specific info, posters should put up their VIN numbers and we can then provide you with info on the particular system you have.
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Re: C4 heater/air con not working

Post by Arthuros-+ »

Thank you for your quick response. I think my problem is elsewhere as there is no power going to the blower at all. Have thought that the blower had gone dead so have purchased one on eBay, had it connected and nothing happened. Then I had the multimeter out and realised that no power is getting trough. All fuses were ok, read a bit more and found that the fuse box is the blame, replaced that but still no juice going to the blower . Then I had it tested with 12v direct and it does work. So somewhere the power is stopped, have checked the wires but they all look in good shape. I am thinking to run a fused direct line from the battery to the blower and put a switch to that if everything else fails. It is raining badly and very quick the condensation gets the windscreen in a mess so I have to open the windows and more water gets in.... Here is the VIN VF7**************[VIN obfuscated, can be read by forum staff]
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Re: C4 heater/air con not working

Post by GiveMeABreak »

So this is your setup: Item 3 is the Blower control module for reference - however, this is supplied directly by Maxi Fuse 6 in the engine fuse box.
C4 Blower Part.PNG
So I would check Maxi Fuse 6 in the engine fuse box - this is a 50A. So if there is no power to it when connected it could be the maxi fuse that has blown. MF6 does not seem to supply anything else.
MF6.PNG
I don't really recommend a direct wire up, as this system is linked to the A/C ECU control and the BSI via the CAN network and may have implications down the line....

Try to see if you can identify the cause first.
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Re: C4 heater/air con not working

Post by admiral51 »

@ Arthuros-+
I had this problem as posted earlier in this thread and the bridge trick worked, however in another post which i will try to find i had major issues with the fuse box which resulted in a breakdown and recovery home.
I notice you say you have replaced the engine fusebox but with a second hand unit.
I understand cost are different for each and every member but i went down the route of getting a new unit ( not from Dealers, i am not loaded ) to eleminate the fusebox from any further issues.
Yours is a 10 year old car, so guess the replacement fuse box is probably around the same or similar age so could be suffering from the same problem as your old one.
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Re: C4 heater/air con not working

Post by GiveMeABreak »

Worth checking the Maxi Fuse first - cheapest option for the sake of a fuse.
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Re: C4 heater/air con not working

Post by admiral51 »

GiveMeABreak wrote: 30 Sep 2019, 18:35 Worth checking the Maxi Fuse first - cheapest option for the sake of a fuse.
I agree with that 100%
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Re: C4 heater/air con not working

Post by Arthuros-+ »

I will try the fuse and will let you know. Thank you very much for the information provided!
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Re: C4 heater/air con not working

Post by admiral51 »

As promised link to my problems with my C4 C4 Issues
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Re: C4 heater/air con not working

Post by Arthuros-+ »

Hi, the maxi fuses were all good. Any other suggestions?
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Re: C4 heater/air con not working

Post by GiveMeABreak »

Ok, so if we know the blower motor is working under direct control - there must be an intervention in between that is preventing the power getting through. A diagnostic with diagbox would probably help at this point, given the tight integration of the system with other components.

Here is the wiring diagram for the heating system for your Picasso.

8045 is the actual Blower Motor.
Wire 8018: blower control module requirement
Wire 8019: blower control module diagnosis
Wire 8020 : air conditioning motor control

Wire 8020 above goes to 8048 which is the Blower relay
Wire BF01B: is the wire that goes to Maxi Fuse 6 that you say you checked as being OK.
Wire BM11B: (11 fuse server unit) is the internal relay (R7) of the engine fuse box.

Looking at the diagram again - I can see that Fuse F11 in the engine fusebox is for the blower relay So definitely worth checking that. It should be easily accessible and is located here where I have arrowed it in Green:

Click Image to Zoom
F11.PNG


Image
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Re: C4 heater/air con not working

Post by admiral51 »

I spoke to the garage i use today to try and clarify what i was told by them when i had issues with the C4 fusebox.
They will remove the current fusebox and split it in 2 by using a hot knife around the seam and clean up the internal connections and then reseal the fuse box.
I trust them and when you look at the costs of a new unit from Citroen compared to the cost of 2 hrs labour +vat =£130 some people may take a punt on it, but even they would not guarantee that it would solve all the problems.
They advised a new unit, as posted in my other thread i wanted a clean install to remove the fusebox as an issue,and Marc put me in touch with a reliable and cheaper supplier than Dealers of a new unit.
I still think you have an issue with the fusebox, even though it has been replaced, it is all down to cost and that is a personal issue
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Re: C4 heater/air con not working

Post by Arthuros-+ »

Hi, will test it again with the clone diagnosis. Has some bsi reinitialization code. Also after fitting the sh fuse box the screen washer pump worked again so something good came out of it. Will try cleaning the old fuse box splitting it in two and maybe it will work...
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