Heating not working

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DanCD
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Heating not working

Post by DanCD »

Hello everyone,

Apologies if this has been covered elsewhere in the forum, I've found similar issues but not specifically the same as mine.

Over the past few weeks I have been having a coolant leak issue on my Citroen C4 1.6 VTi exclusive 2011 and subsequently put some K-seal into my expansion tank for a temporary fix. This did stop the coolant leaking but as this was only temporary I took it to my local Citroen dealership and they found it to be due to a leaking thermostat housing which they replaced.

However, my heating isn't working (I'm not sure if it was working before the thermostat was replaced as I've not used it for a while). The fans are blowing but the heating only gets lukewarm even after the engine has had enough time to get to operating temperature. I was thinking, could this be a blocked heating matrix? and could this have been blocked by the K-seal I put in?

Does anyone know where the heating matrix is on this car and whether this would be an easy job to unblock or repair myself?

Many thanks,
Dan

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GiveMeABreak
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Re: Heating not working

Post by GiveMeABreak »

Very possible - a bit late now, but never I would never use such products in the heating systems of modern cars - it is essentially gunk and can easily clog up the fine capillaries of the matrices. Despite their claims I would never use it.

An Example:

https://www.kwecars.com/jaguar-tech-cen ... -sealants/

Essentially these sorts of sealers are ok in liquid form, but as soon as they hit any air, they solidify - trouble is if you have any air trapped inside the heating system - then the same will happen and that will soon lead to blockages and damage in the long run.

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Re: Heating not working

Post by wheeler »

I've used a few different cooling system sealants over the years mainly as temp repairs but there have been a few times it has outlasted the car. I have found K-seal to be the best by far & its the only one i would use now & never had any issues with blockages. If it is used correctly you shouldn't have any problems. What you need to be careful of is that you give it a really good mix up, it can clump up in the bottle when its been sitting on a shelf for ages. I prefer to mix it up in a separate jug with warm water to help it dissolve, obviously that's not always possible in an emergency & if i have to use it straight out the bottle i would shake it up for at least 5 minutes before pouring it in.
Did you give it a really good mix up before pouring it in? if not then it may have blocked the matrix.

DanCD
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Re: Heating not working

Post by DanCD »

Just as I thought. Didn't occur to me it could block the heater matrix until it was too late. Oh well, you live and learn.

I did shake the bottle for a minute or two, but probably not enough!

Do you know where the heater matrix is located? And whether replacing it is an easy(ish) job?

DanCD
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Re: Heating not working

Post by DanCD »

Hi,

Could anyone give me the part number for the heater matrix of my car? CITROËN C4 II Hatchback 1.6 VTi 120, 2011 reg.

Cheers,
Dan

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Re: Heating not working

Post by Dormouse »

before you bite the bullet try disconnecting the two heater hoses and reverse flush with a hose in the return pipe to see if the core will clear. failing that empty the heater matrix then put the hoses up (using extension hoses if necessary) pour in mr muscle drain unplugger and let it sit for a while with the matrix full. then reverse flush to see if that helps. the matrix is knackered anyway.

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Re: Heating not working

Post by Dormouse »

PS your radiator may have lost a few gill tubes too with clogging. bear that in mind for the future if overheating comes to the fore

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Re: Heating not working

Post by Dormouse »

the heater matrix is the first part to take coolant until the thermostat opens, then the stuff flows fully into the main radiator. if anyone has a heater with the good old fashioned heater valve, put the valve to shut (cold) when you put in radiator sealant and leave it shut until after you have done one full hot run and cooled down. if you have an air blending heating system you are stuffed cos the heater matrix is usually part of the initial cycle and you would need to block off the heater hoses manually and you might not be able to run the car only warm up the engine.

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Re: Heating not working

Post by Dormouse »

having had a quick look at C4s, it might be worth doing the mr muscle twice before changing the matrix! The moral of your story for everyone else reading this is - try and find the leak before you use radiator sealant.
radiator sealant does just what it says on the tin. it will try to seal up every small restriction it finds -- leak, gill tube or otherwise --- permanently.

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Re: Heating not working

Post by DanCD »

Dormouse wrote:
02 May 2021, 17:13
before you bite the bullet try disconnecting the two heater hoses and reverse flush with a hose in the return pipe to see if the core will clear. failing that empty the heater matrix then put the hoses up (using extension hoses if necessary) pour in mr muscle drain unplugger and let it sit for a while with the matrix full. then reverse flush to see if that helps. the matrix is knackered anyway.
I've tried the flushing/ reverse flushing today and let the water run until I could see the fresh water coming through both times but the heating is still blowing out cold air.

I'll have a go at using the Mr Muscle drain unplugger first but like you say, the matrix is probably knackered so I might as well just install a new one.

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Re: Heating not working

Post by Dormouse »

Is the water flowing freely? because if it is you should be getting heat or at least some. IF SO - haud the digger! there might just be something else.
free flowing means little or no real back pressure at the hose end. there will be some from the gill tubes in the matrix but the hose outlet ( the heater inlet pipe) should feel nearly about the same as the hose inlet ( the heater outlet pipe ) If there is a clear difference in pressure the matrix is restricted. if not then the lack of heat might be not be related to matrix restriction and is a coincidence.

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Re: Heating not working

Post by Dormouse »

Other members out there - what can cause low heater output. Is there a linkage/mechanical answer to this heater temperature problem?

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Re: Heating not working

Post by Dormouse »

With the hoses connected can you feel heat in the inlet AND outlet hose. Have the air pockets been bled out? Have you run the engine to full working temperature?

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Re: Heating not working

Post by DanCD »

Dormouse wrote:
02 May 2021, 19:01
Is the water flowing freely? because if it is you should be getting heat or at least some. IF SO - haud the digger! there might just be something else.
free flowing means little or no real back pressure at the hose end. there will be some from the gill tubes in the matrix but the hose outlet ( the heater inlet pipe) should feel nearly about the same as the hose inlet ( the heater outlet pipe ) If there is a clear difference in pressure the matrix is restricted. if not then the lack of heat might be not be related to matrix restriction and is a coincidence.
It looks to be flowing freely, I observed quite a bit of crud come out of both the inlet and outlet pipes when flushing and the flow did increase once this had been removed and the water became clear.

I might give it a second and third flush tomorrow

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Re: Heating not working

Post by GiveMeABreak »

DanCD wrote:
02 May 2021, 17:00
Hi,

Could anyone give me the part number for the heater matrix of my car? CITROËN C4 II Hatchback 1.6 VTi 120, 2011 reg.

Cheers,
Dan
Hi Dan

Part for the Heater Matrix on your C4 is 6448W8. Item (1). It is priced today at £226.21 inc. VAT from Citroen and includes all the items highlighted.
C4 Matrix.PNG