DS3 reduced Air flow from Dashboard Vents, Air Con System icing up on two cars !

[iholly01]

Thanks firstly for reading this !

Has any one come across this problem we are having with both of our DS3’s before I wonder?

Driving around normally at around 20-30 mph and both heater and AC work exactly as they should adjustable from freezing cold right up to very very hot. Blower motor works fine on all speeds and also the Auto / Climate control works and keeps the car at whatever temperature you select.

When driving at motorway / dual carriage way speeds again , starting out and everything is fine. AC nice and cool and a good volume of air or good air flow from all the vents. The problem comes after sometimes only about 15 mins driving at these speeds and if using the AC you will start to feel the air temp in the car getting warmer and continue to do so while at the same time the air flow from the Centre dash vents reduces to a point where there is hardly any air flow at all coming out,

At this point the Air flow even though it is still cold has reduced in volume and is no longer sufficient to keep the car interior cool and another point to note is that the noice from the Heater system increases similar to when using the recirculation mode only louder, Much louder! Very much sounds like the heater blower motor is trying to work but the air system is sealed?

Once the heater system has got to this point then the only solution I have found is to turn the AC off and increase the Temp on the heater controls right up to High (Hot) at which point the Noise from the blower motor reduces while at the same time the control flap I am guessing redirects the airflow within the heater body to pass over the heater matrix and warm the flow of air. The volume of air coming out of the vents dramatically increases to a point where it would be normally and the centre dash air vents start spitting out small bits of ice and moisture which I assume are from the Evaporator which is now being being able to defrost itself.

Give it a few mins like this, reduce the temp back to low switch the AC back on and all will be fine again, icy cold air and happy passengers for another 15 mins, sometimes longer and sometimes for the rest of the journey.

My theory is that either the recirculation flap or the temp mixer flap within the heater is either getting stuck or the stepper motor is failing/ jammed / stripped the teeth on its gearing etc. This combined with the pressure from the air flow passing into the heater as the car is being driven at higher speeds is causing the flap(s) to close even further which then reduces the air flow to a point where there is not enough flow over the evaporator coils to prevent it from freezing which it then does adding to reduce the air flow further.

The fix I mentioned about moving the flaps to hot seems to get everything moving again and allows the evaporator coils to defrost before sooner or later this fault happens again.

Thankfully in a way this is not a fault that occurs randomly and I can relocate it pretty much every time either of the cars are driven at say +50mph the only thing that varies is the amount of time it then takes before this fault happens but normally it is around the 15-20 min point.

The AC pressure is totally spot on for both cars, have checked this and both the High side and Low side pressures are good for the system. Never had any leaks or problems and all been fine up until this issue. Cabin / pollen filters I change twice a year but to be honest even driving without them installed makes no difference.

I have tried the reset for the flap motor positions via the Dash board controls and have also had the cars on Diagsoft / Lexia to perform a reinitialisation of the flap motors so they can reset the end stop positions etc and all pass fine but I am guessing the motor is taking its position reference from the spindle / shaft and not from the relevant position of the flaps? So it could think that it is in a position when really it isn’t maybe? And this is where my suspicions are for the fault at this moment.

Has anyone else come across this or a similar fault ? Having it happen on one car could be down to just one of those things but now both of the DS3’s here are doing the same thing then I am thinking its more than coincidence and someone else must have come across this before?

I am more than happy to start swapping out motors etc for the heater assembly but any pointers as to which would be a good start would be appreciated or indeed if you think maybe my thoughts as to the cause of this problem are incorrect then I would be really grateful for any info.

I will say they both have been great little cars ignoring the snapped coil springs, paper thin exhaust hangers but recently after having to replace the Ad Blue Tank and Nox Sensor on the blue Hdi one I would rather not spend endless amounts of money throwing parts at them and hence I would appreciate a second opinion if any one has the time.

Thanks for reading , double thanks too if you have any suggestions and apologies for those of you that may have the same problem as I know how you felt with the heat of this last week !!

[mickthemaverick]

Since this sequence is happening in both your cars I can't help thinking it may well be a systemic problem which arises in the cars at a given point. Have you spoken to the DS dealer to see if they are aware of it?

[iholly01]

Thanks for the reply and I agree with your thoughts re it being a systemic fault.

I have spoken to a local dealership how have offered to perform a diagnosis but talking to their service manager he basically said they would carry out the same diagnosis that has aleerady been performed with Diagsoft / Lexia and thing from there. The only difference obviously is they have access to parts but the offset is the cost of the diagnosis / labour that we would have to cover basically to get to the point we are already at.

I am convinced it is a restriction of Air flow into the heater that is causing it the tricky bit is finding out the part that starts the chain of events.

The first car started to do it intermittently about a year ago and it's probably been the last 4 months that the second one has been displaying the same problem.

It may well have been doing it before but with the weather being cooler and short journeys mostly it would not be that obvious until like now the weather has warmed up.

Will keep a watch here for any suggestions and keep digging at it and when I get a result I will post it back as I am sure others may well face this sooner or later eh!!

Cheers

Ian

[PaulC5]

I do not know the year of your cars but on our 2010 C3 we had the heater unit replaced as one of the flaps kept seizing. This was a manual system not auto climate control and the cable from the temperature knob kept bending and not moving the flap. Expensive job though.

[iholly01]

I do not know the year of your cars but on our 2010 C3 we had the heater unit replaced as one of the flaps kept seizing. This was a manual system not auto climate control and the cable from the temperature knob kept bending and not moving the flap. Expensive job though.

Cheers for that Paul and yes, I can image it would be given the amount of plastic trim, dash etc that would need to come out first before even getting to the heater matrix. I have not looked that far into it yet as to be honest if it came to that it would probably not be worthwhile considering it.

I think though it could be an age / wear related issue as the first car to have the fault is a 2014 and the second one is 2015 or 16 (can never remember lol). The newer one has probably had more use in the last year and thus now its caught up it terms of use with our first and thus is exhibiting the same fault / symptoms.

I will keep banging on at it though and update this if I manage to get a fix.

[RichardW]

Our Mk 1 Picasso used to do this. The evaporator shouldn't ice up as the control system should cut (or control depending on the system) the compressor once the temp gets close to 0C. Check in Diagbox what the evap temp is reading - my thoughts was that it had fallen off the evaporator or the reading had drifted. I never fixed it as it only did it after a longish run on hot days, and just knocking the AC off for 10 mins allowed it to defrost.

[iholly01]

Our Mk 1 Picasso used to do this. The evaporator shouldn't ice up as the control system should cut (or control depending on the system) the compressor once the temp gets close to 0C. Check in Diagbox what the evap temp is reading - my thoughts was that it had fallen off the evaporator or the reading had drifted. I never fixed it as it only did it after a longish run on hot days, and just knocking the AC off for 10 mins allowed it to defrost.

Hi Richard, thanks for that, I Had not thought to check the temp of that but will do now you have mentioned it.

Your solution in turning off the AC achieves the same as my turning the heaters up to Hot at the same time as switching the AC off in so much as a quick defrost and then back to normal. The only anomaly is that sometimes when I have done this the system can then work perfectly for the rest of the journey of + 2 hours or so and then other times it will freeze back up within 15 mins. That is the only unpredictable part.

The sensor though is something I had not considered so will check that out even if only to remove it from the list of possible causes eh !!

Like you, when this started happening to the first car here I was not too bothered and put it down to one of those niggles but with the second doing it now I think its time for me to spend a bit more time in trying to figure it out hopefully.

Thanks again for the reply and suggestion

Ian