C4 Failing heater core/matrix?

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Wobbleboard
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Joined: 08 Jul 2020, 09:53

C4 Failing heater core/matrix?

Post by Wobbleboard »

Morning,

Have just joined up and said a hello, but am looking for some knowledge more than anything. I have a 2016 C4 diesel, had it for 3 months now (purchased from an approved Citroen dealer a day before lockdown) and have a problem I'm really not sure of.
I have already had an emissions failure and the countdown due to the adblue system which is still awaiting replacement under warranty, but the sensors have been reset so is fully driveable currently, but then 3 weeks after that I was cleaning the car and found the drivers footwell to be very wet under my mat. It had been dry before it went in for the adblue sensors, but I can't say for sure when it started as it was under the mat and only seen when cleaning.
I have taken it back in and due to the current pandemic the dealership garage is not able to assess the problem as they are not permitted to run the heaters or air con, but when they can it needs to be in for 3-4 days, seat removal, carpet removal, dashboard removal and being put in a heat room to dry out, major pain and in the meantime nothing can be done, oh and they are not sure if it is covered under their warranty (so much for a newer, more reliable car with warranty for peace of mind!)
They inform me it isn't related to work done on the adblue system/systems, but is coolant leaking from the heater core somewhere, now I'm not sure, the liquid is colourless and odourless, my coolant levels in the expansion tank have not dropped and I can control the amount of wetness by not using the auto function and A/C and keeping the fans on low. I have been able to get the carpet about dry and with low fans and no A/C they are only damp, turn that up and within the day when being used I am paddling, but still not needing to top up the coolant.
Knowing nothing of the system I'm asking if the coolant would flow through the matrix at a permanent rate, therefore leak at a permanent rate, or if it really is dependant on fan/heater/AC use. I just have my doubts over it being coolant?
Hope that makes sense and thankyou.

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GiveMeABreak
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Re: C4 Failing heater core/matrix?

Post by GiveMeABreak »

My first thoughts were the heater matrix - but you should notice an odour or your water / coolant levels dropping (depending on how much water has come out). But that would probably have water coming out on the left side of the floor as that is generally where the matrix is located. But if not this, it may be possible that the drain pipe for your evaporator has become blocked / split / damaged / moved, so instead of the water draining out through the pipe and underneath the outside bottom of the car, it may be running down the outside of the pipe (if it is leaking from where it leaves the evaporator), and finding its way down into the right hand side of the foot well, as the pipe flows from the right hand side of the evaporator.

So worth getting them to check the AC Drain pipe first.

Hell Razor5543
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Re: C4 Failing heater core/matrix?

Post by Hell Razor5543 »

Sometimes, with a leaking heater matrix, people have said they have smelt a 'curry' smell. If you can smell that it does point to a leaking matrix.

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GiveMeABreak
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Re: C4 Failing heater core/matrix?

Post by GiveMeABreak »

He's already said:
Wobbleboard wrote:
08 Jul 2020, 10:35
the liquid is colourless and odourless, my coolant levels in the expansion tank have not dropped
So on that basis I suspect it is the condensation from the evaporator that is not being evacuated / AC Drain pipe. Sometimes these can be unblocked by getting the garage to shoot a small amount of compressed air up the AC Drain pipe tube from the outside of the vehicle and this can unblock it.

As you said it only seems to happen when the A/C is turned on, I think we can rule out the water drains from the outside air scuttle area which can become blocked with leaves and crud. These drains usually evacuate the water down and out from the wheel arches, where there should be a couple of small flaps.

Wobbleboard
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Re: C4 Failing heater core/matrix?

Post by Wobbleboard »

Appreciate the feedback, I suspect it is the A/C drain as opposed to coolant leak, and even when I called them up originally they said instantly the air con system. It is definitely not the scuttles, I had that in my DS3 so was the first call, I poured water in and it instantly drained to the road on both sides.
Unfortunately the dealership say they can't look at it properly until restrictions are lifted to confirm anything, so may take it to my local and ask them to do a quick check on the drainage pipe, could really do without the need to strip out the seats and carpets and drying for days the dealer is proposing, plus it is odd it appears to have occurred around the time they looked at the last problem, but they swear it is opposite ends of the car for work on error codes U3FFF fuel high pressure circuit and P2201 Nox sensor, measurement of the sensor blocked, maybe it is coincidence, but I keep thinking a knocked pipe?
Anyway thanks again.