C5 X7 2010 HDI heating problem

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mihkel
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C5 X7 2010 HDI heating problem

Post by mihkel »

Hey!

I've got a 2010 C5 (X7). It's a 2.0 HDI (RHR) with the factory aux heater as well, was it Webasto?

The problem is with cabin heating when the temperatures drop below -5*C. The aux heater is working fine and starts up every time in colder weather. I get initial heating quite quickly, but it does not get warm, far from it. It takes about a 2 hour trip to feel yourself comfortable. And that is way too long. I won't even talk about colder weather.

I've checked the heater core pipes and they get hot, too hot for touch. But weirdly both supply and return pipes are hot. Both sides of the car behave the same way. Fiddling with the controls does not give any better results than auto. Is there any flaps to blame?

I've got Lexia/Diagbox to help with some diagnostics if needed. If I recall correctly then there were no faults in the climate unit last time.

And another undiagnosable problem with starting system. Once per let say 50 starts the starter cuts out in the middle of staring and the engine does not start. If it happens, it keeps cutting out before starting. Only help is to give it a little gas or disconnecting the battery for a while.
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Re: C5 X7 2010 HDI heating problem

Post by GiveMeABreak »

I'd be looking at your heater matrix or the air distribution mixer flap or stepper motor.
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Re: C5 X7 2010 HDI heating problem

Post by mihkel »

As per this diagram I understand that there 2 flaps and stepper motors per side? Parts 1; 2; 3.
http://www.catcar.info/citroen/?lang=en ... BwbGllcj09

So there would be four flaps? If so - then two flaps should be leaking cold air into the vents. Is that possible?
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Re: C5 X7 2010 HDI heating problem

Post by GiveMeABreak »

Depends entirely on your vehicle options as to whether you have mono or dual zone Climate. I would be cautious of that website - they use old data from old offline sources that are at least 9 years old....

PSA do not provide their data to these people officially.
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Re: C5 X7 2010 HDI heating problem

Post by mihkel »

I've used alternatives since the "official" site went paid.

And the climate system is dual zone. Today it was -25*C. It wasn't much colder in the car. I tried recirculation which was a bit warmer. It seems to me that not enough air is passing through the vents. For information the cabin filter has been changed.
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Re: C5 X7 2010 HDI heating problem

Post by GiveMeABreak »

I'm just saying the info is out of date... but as long as you know this.

You have both Air Distribution and Air Mixing motors on the left and right side and an additional air intake stepper on the right side.

Diagbox should be able to confirm what is or isn't working from testing the system.
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Re: C5 X7 2010 HDI heating problem

Post by Xantippa »

If it blows cold in the summer normally, maybe heater matrix is blocked from coolant sealant that some previous owner has used too much?

Is outside temperature sensor ok, so it shows real temperature not too warm?
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Re: C5 X7 2010 HDI heating problem

Post by mihkel »

A year has passed and I still have not looked into the problem in more depth.

The temperature sensors do work.

I'll have to check the readings of temperatures and flap positions when I get the time.

One thing that i have found out - the two zone climate control temperature readings (left and right) don't show the desired cabin temp. If I crank it up to 27 or HI then it gets much warmer but still nothing compared to normal conditions.

It's a pity because the auxiliary fuel heater starts up at low temperatures but non of that heat comes to the cabin. If the diagnostics don't show anything then it might be time to change the heater matrix. Mahle or original? 50€ vs 150€
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Re: C5 X7 2010 HDI heating problem

Post by Ross_K »

Hey Mihkel, maybe take off the panel in the passenger side footwell and check if the pipe going into the heater matrix gets hot?
Ross_K wrote: 08 Nov 2022, 18:14 Image
See this thread: viewtopic.php?t=72851

You could try to flush the matrix to remove any gunk but if you're reasonably sure that the last owner blocked it by using too much sealant, you might as well just go ahead and fit a new one. Of course check the flaps using Diagbox also :lol:
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Re: C5 X7 2010 HDI heating problem

Post by mihkel »

The panel has actually been off over a year :-D It shows the determination I have to solve the issue.

Today I measured the temperatures with an IR temp gun from the engine bay. The pipes in the footwell can't be measured correctly, the gun was showing way too low numbers. One of the pipes is too hot for longer touch, the other one is ok to touch. Diagbox diagnostics are still to be done.

Outside temp -5*C
Engine temp 80*C (thermostat is 83)
Inlet to heater core 60*C
Return from heater core 45*C

The blower motor was running at half speed. If I crank it all the way up, then the return temp drops about 5*C more. Seems to me that there is not enough coolant circulation. I'll get some more reference when I'll test my older Volvos temps. 2.5 diesel, no webasto and heats the cabin quite quickly around -10*C.
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Re: C5 X7 2010 HDI heating problem

Post by mihkel »

Diagbox did not show any faults. Heat mixer damper motors were moving fine and working (0-100%). The only weird thing was that the passenger temp sensor in the ducting showed something about 6300*C :-D, driver side was working fine. It could be diagnostics fault as well.

The test on the other car showed a bit different numbers:

Outside temp -5*C
Engine temp 80*C
Full blast blower and heat
Inlet to heater core 72*C
Return from heater core 61*C
Ventilation duct was at 62*C (On the Citroen the maximum I got was 35*C)

Medium speed and heat
Inlet to heater core 74*C
Return from heater core 67*C

So a 7-11*C drop in temperature across the core and low duct temperature. So I might start looking into changing the heater core. Has anyone got info on the replacement? Seems to be easily replaced as it can already be seen, but I guess I should be more cautious.
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Re: C5 X7 2010 HDI heating problem

Post by Ross_K »

mihkel wrote: 23 Nov 2022, 10:15 The only weird thing was that the passenger temp sensor in the ducting showed something about 6300*C :-D, driver side was working fine. It could be diagnostics fault as well.
Huh that seems weird. If the sensor's cheap and easy to replace, I'd probably do that and re-run the diagnostic before taking the time to change the heater matrix.

Anybody else have any ideas on this?
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Re: C5 X7 2010 HDI heating problem

Post by mihkel »

This kind of a reading should throw a code. So I suspect that this is just a diagnostic equipment quirk. Nevertheless the flaps work fine when the two dials are turned so I wouldn't think I'd go into that.

According to this post the replacement of the heater matrix is quite straight forward:
https://www.drive2.ru/l/537905828393387441/

Google translate does wonders when English sites do not have any information on the job at hand :wink:
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Re: C5 X7 2010 HDI heating problem

Post by mihkel »

I HAVE HEAT!!!

Can't be happier :rofl2:

Took on the job today and replaced the heater core. Took some hints from this video:


But I'm a lazy guy and I did not bother to remove the center console. I cut the the dash bracket the same way with an pneumatic grinder. Be sure to cover up everything close by - a lot of sparks! Drained the coolant and took the heater core out, easy! But I did not like the way the bracket was fixed afterwards in the video. I welded a 4mm bar to the cut piece and drilled 9mm holes for 2x M8 bolts and one extra hole to the car side bracket.

I even contemplated cutting the heater plastic enclosure from the passenger side but I was not sure it would pull through.

I've now got 63*C coming from the vents and only a 5*C drop across the heater core input and output on full blast. The old heater was clogged really bad. I could hear coolant sloshing around in there but not much came out. I cut one of the heater sides off. I could see some kind of brown gooey residue in the bottom part and scale "rocks" blocking the channels. That's what you get from a half a million kilometer car with no good service history. Could be some kind of a "leak block" or somebody has used tap water in the cooling system.

The new Mahle heater core was only 55€ - happy days!

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Re: C5 X7 2010 HDI heating problem

Post by myglaren »

Excellent result.
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