Citroen c5 X7 - cabine heating problem?

[Jay-Bruce]

This thing:

That's not it surely, in front of the pollen filter, with the pipes going in? That'd be too accessible for a Citroen

Ross!! Really? I can't believe, an experienced citroenian such as yourself fell for that old trap - just because you can see it, sometimes even if you can get your hands on it, doesn't mean you're going to be able to extricate it. It's french, it's a car, ergo its female, so it's a french female, and you know how provocative and seductive they can be, it's teasing you... you probably need to remove the dash to get the mofo-matrix out.

[Jay-Bruce]

Hi guys, I have possible problem (still not sure is it normal or a problem) with the cabin heating. As we have entered November the temps have dropped enough for the cabine heating to be used. That said, I just can't get enough heat, no matter which temperature I set.

I have an C5 Exclusive from 2010 with auto a/c. I did noticed that when set to 28 it's a little bit warmer, however it's not warm, more like lukewarm. I've read that some people could not seat in their C5's when set to max temp.

I had BX and C5 mk1 (2002) and setting the heating to max would make you wanna jump into cold river.

Is this normal behavior?

Thanks for all the answers.
Mladen

You've got 3 C5's listed in your profile, which engine is in the one with the poor heater? Reason I ask is depending on what engine is in there it might be easier to backflush the heater matrix by removing the hoses from the engine bay to cabin firewall/bulkheadand blast through it with a garden hose or pressure washer or something to backflush the heater matrix?

[darbuck]

Sounds like you need a new thermostat the old one has failed open

[CitroJim]

Ross!! Really? I can't believe, an experienced citroenian such as yourself fell for that old trap - just because you can see it, sometimes even if you can get your hands on it, doesn't mean you're going to be able to extricate it. It's french, it's a car, ergo its female, so it's a french female, and you know how provocative and seductive they can be, it's teasing you... you probably need to remove the dash to get the mofo-matrix out.

Many a true word spoken in jest Reminds me of all the Xantia heater matrixes I did... You'd think the whole car was built around the heater matrix... What a job! A full day of tedious work...

[Jay-Bruce]

You know it'll be trouble if it is french and has wires, or boobs, or tyres.

[Hell Razor5543]

Ross!! Really? I can't believe, an experienced citroenian such as yourself fell for that old trap - just because you can see it, sometimes even if you can get your hands on it, doesn't mean you're going to be able to extricate it. It's french, it's a car, ergo its female, so it's a french female, and you know how provocative and seductive they can be, it's teasing you... you probably need to remove the dash to get the mofo-matrix out.

Many a true word spoken in jest Reminds me of all the Xantia heater matrixes I did... You'd think the whole car was built around the heater matrix... What a job! A full day of tedious work...

As I understand it first the heater matrix is placed into the jig, and then the bodyshell is bolted onto it, followed by the other bits 'n' bobs.

[Ross_K]

You've got 3 C5's listed in your profile, which engine is in the one with the poor heater? Reason I ask is depending on what engine is in there it might be easier to backflush the heater matrix by removing the hoses from the engine bay to cabin firewall/bulkheadand blast through it with a garden hose or pressure washer or something to backflush the heater matrix?

Good idea!

I found a nice YouTube vid showing how to do a flush with a garden hose:



The only difference being that's an American pickup truck so he's got loads of space to access to the inlet and outlet pipes...something you're unlikely to have in a C5

Worth noting that the flush did make a nice difference to the cabin temperature

You know it'll be trouble if it is french and has wires, or boobs, or tyres.

Own an Alfa and you can have problems with all of the above, plus rust...

[ExOduS442xb]

You've got 3 C5's listed in your profile, which engine is in the one with the poor heater? Reason I ask is depending on what engine is in there it might be easier to backflush the heater matrix by removing the hoses from the engine bay to cabin firewall/bulkheadand blast through it with a garden hose or pressure washer or something to backflush the heater matrix?

Hi Jai, my vehicle is 3.0 HDi and my father's is 2.7 hdi, both cars have the same problem, and he put new coolant in 2021.
But this idea might actually work, this is what Marc was talking about, and this actually might be doable!

Ross thanks for video, I actually continued searching for similar YT videos and found another from famous Scotty: https://www.youtube.com/watch?v=5bIpXvHNQbQ

It ain't easy to reach the hoses, but I did found them. I have an idea, I will drive the for about 15-20min to get the temp to operating levels, then I will stop the car and set the heat to max and blower to max and reach for the pipes, both pipes (IN/OUT) must be hot, if one doesn't get hot then I think we located the problem.

Edit: I will remove the plastic protection below the driver to get to the pipes, both should be hot, this is actually the easiest way to check I think.

[citroenguy]

You've got 3 C5's listed in your profile, which engine is in the one with the poor heater? Reason I ask is depending on what engine is in there it might be easier to backflush the heater matrix by removing the hoses from the engine bay to cabin firewall/bulkheadand blast through it with a garden hose or pressure washer or something to backflush the heater matrix?

Hi Jai, my vehicle is 3.0 HDi and my father's is 2.7 hdi, both cars have the same problem, and he put new coolant in 2021.
But this idea might actually work, this is what Marc was talking about, and this actually might be doable!

Ross thanks for video, I actually continued searching for similar YT videos and found another from famous Scotty: https://www.youtube.com/watch?v=5bIpXvHNQbQ

It ain't easy to reach the hoses, but I did found them. I have an idea, I will drive the for about 15-20min to get the temp to operating levels, then I will stop the car and set the heat to max and blower to max and reach for the pipes, both pipes (IN/OUT) must be hot, if one doesn't get hot then I think we located the problem.


Edit: I will remove the plastic protection below the driver to get to the pipes, both should be hot, this is actually the easiest way to check I think.

Have you checked PTC heater? Without it it will be cold

[Jay-Bruce]

on other vehicles I've encountered PTC's on, their purpose is only to run for a little bit to allow heat out of the vents before the engine coolant has any worthwhile heat in it. Usually their control logic switches them off once the coolant temperature reaches a certain threshold.

[ExOduS442xb]

Update: I think I found the cause, it looks like you guys were right. I drove the car for around 15-20min and removed the plastic cover below the steering wheel, set vent to max speed, set temp to 28 and to HIGH and touched both hoses going into heater matrix, one metal hose is so hot that you can't hold your finger on it for more then 1sec (if that) however the other is actually cold/mild temp. I did the same thing in the engine compartment just to confirm this again, the one going in is extremely hot, but the other one is lukewarm-cold.

Have you checked PTC heater? Without it it will be cold

Unfortunately I was unable to reach it but since there is some heat going in, I am assuming this is working!

Now, since I am pretty sure this is the problem, how does heater matrix work?
Is there some kind of valve that controls how much coolant will be released into the heater matrix?

[Jay-Bruce]

You've got 3 C5's listed in your profile, which engine is in the one with the poor heater? Reason I ask is depending on what engine is in there it might be easier to backflush the heater matrix by removing the hoses from the engine bay to cabin firewall/bulkheadand blast through it with a garden hose or pressure washer or something to backflush the heater matrix?

Hi Jai, my vehicle is 3.0 HDi and my father's is 2.7 hdi, both cars have the same problem, and he put new coolant in 2021.
But this idea might actually work, this is what Marc was talking about, and this actually might be doable!

Ross thanks for video, I actually continued searching for similar YT videos and found another from famous Scotty: https://www.youtube.com/watch?v=5bIpXvHNQbQ

It ain't easy to reach the hoses, but I did found them. I have an idea, I will drive the for about 15-20min to get the temp to operating levels, then I will stop the car and set the heat to max and blower to max and reach for the pipes, both pipes (IN/OUT) must be hot, if one doesn't get hot then I think we located the problem.


Edit: I will remove the plastic protection below the driver to get to the pipes, both should be hot, this is actually the easiest way to check I think.

I see what you mean about the access, that's going to be a bitch to get on to them.

[Ross_K]

Now, since I am pretty sure this is the problem, how does heater matrix work?
Is there some kind of valve that controls how much coolant will be released into the heater matrix?

I'd expect you should find a control valve on the inlet pipe.

One of the two light-grey un-numbered items in this diagram maybe? Perhaps the one on the left?

[citroenguy]

Since this is a "modern" (post cirka 1995) there is always coolant flow through the heater matrix.
The temperature is controlled only by the flaps in the heater box.
As you can see in the above picture there is no valve in the system.

The last Citroën with heater valve was the BX

[Ross_K]

I didn't know that. Thanks for clarifying!