C4 Picasso 2015 (B78 plate) Heating problems

[Slaay]

As I understand they move the arms (14), or not?

[Chris570]

Just to add to this, I have the same year of car and I STRONGLY suspect a blocked heater matrix (as it was for the original poster). Citroen actually changed the matrix for this car in later years so it may be a known fault.

I'll be pulling my matrix soon to confirm if it's blocked or not (my flaps are moving as they should as well as it goes from ICE cold to cold)

I agree though that earlier cars are well known for broken flaps so never say never!

[GiveMeABreak]

If it’s not the motors, then it will likely be the spindle that has worn at the gear end. Overtime the constant heating and cooling of the air mixing box causes the plastic to stress and warp, and this makes the spindle harder to turn, until it eventually snaps or wears the female part of the gear socket.

[Holleybush]

Hi all,

I found this site whilst looking for a solution to my C4 problem and it's very similar to this topic so was hoping for some advice.

My heating is playing up, passenger side is fine, drivers side is always cold. In the cold mornings I have to close vents on my side and warm the car up with the driver side vents.

I spent today pulling all the covers off and have learnt a lot (like getting the damn covers off!) but I'm still unsure of the issue. When changing the temp on each side independently the motors turn the cogs correctly, and I can see the flaps moving through the plastic so I don't think it's a control issue. I even forced the cog for drivers side by hand to be sure it was fully activated but drivers side (including rear seat vent on drivers side) is still always cool compared to passengers side.

I've found the pull out resistor matrix (I think that's the name!) that pulls out from the left. And behind that the heat exchanger which has the fixed pipes going to it.

But I don't understand where the split for passenger and driver side air occurs as the heat exchanger and resistor matrix look shared. Hence I'm a bit reluctant to try the resistor matrix or heat exchanger before getting more info as they're not particularly cheap.

Hopefully this makes some sense, I'd be grateful for any advice.

P.s. my car is a Citroen C4 Grand Picasso Blue HDi 150 2015.

Thanks!

[GiveMeABreak]

Depending on the climate system fitted, you will have air distribution motors and also air mixing motor. It won't be anything to do with either air heating resistance (so supplement the cabin heating on a cold day) or the heater blower module, as this just controls the seed of the blower motor.

It is therefore likely that one of your air mixing motors or the gearing has sheared on the driver's side has failed (if this is the side that is remaining cold), leaving the air temperature set on the last setting before the motor or gearing packed up.

[Holleybush]

Thanks for the quick reply!

My system looks very similar to the schematic you posted on page 1. I did watch the motors drive the cogs earlier but I'll have another good look at them tomorrow. I'll give an update once I've found something....

[GiveMeABreak]

Ok, so if you are watching the mixing motor on the driver's side and the cogs are turning, then it is likely the gearing on the spindle has worn and not moving the flap.

[Holleybush]

Yeah, it was my first time looking at this heating assembly and I was trying to work out which motor was doing which job by adjusting the temperature all the way up then all the way down. I'll have a good play tomorrow!

Thanks for the advice.

[agabe]

Hello !

I have about the same problem too with my heating. Hot air is coming from left side panel, and the left side of the middle panel. The right side of the middle panel there is moderate, and on the right side there's almost cold air.
What I found itt looks the heat radiator (or matrix ? ) need to replace.
Can you please send me the part number of it, and the repair booklet for the car ?
The WIN number is : VF7**************[VIN obfuscated, can be read by forum staff]

Thanks,
Gabor

[GiveMeABreak]

It's unlikely to be the heater matrix otherwise you wouldn't be getting significant heating - but as you have heat on one side, it is likely to be the air mixing motor on the right hand side.

[agabe]

It's unlikely to be the heater matrix otherwise you wouldn't be getting significant heating - but as you have heat on one side, it is likely to be the air mixing motor on the right hand side.

The motors was checked by diagbox and all are works like charm. Outside the box everithing moves rotates, and nothing broken.
The spindles are outside or inside the box ?

[GiveMeABreak]

The motors often continue to work, but it's the plastic gearing that wears down, so it just turns in the socket.

[agabe]

OK. Thanks for the advice !
Is it replacable ? The plastic gearing ? How can I find the partnumber of it ?

[agabe]

I just checked, the speed of the ariflow is changing in all panels. If I set the temperature up the airflow speed decreasing , if set down the airflow speed increasing same level both sides all panels. It suggest to me that the air mixing is operating both sides.
Maybe I'm wrong, but I think if the air mixing would not work the airflow speed should stay the same level all time.

[Slaay]

I FOUND THE ISSUE! If you have same problem as me with the heating so that’s the heating matrix. Is a common problem for Peugeot Citroen...the matrix clogs. It starts from the far end (right side) what respond for the right side heating (as the in&out pipes are from left side).
Very important, before you install new matrix you must clean the heating system and change the coolant, otherwise you will have to do this again in couple years:))

Here is a link with some info but is russian language. At least will give you some idea
https://www.drive2.ru/l/8464201/

https://www.drive2.ru/l/9056658