DS4 heating

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white exec
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Re: DS4 heating

Post by white exec »

When the engine is up to temperature, the heater matrix will always run hot, irrespective of what temp has been selected for the cabin. The matrix is connected straight across the engine block/cylinder head, and so runs at the same coolant temp as they do. (Cool or cold air for the cabin is achieved by the heater flaps altering the air path.)

With the cabin fan switched off (so there is no fan cooling), both pipes at the matrix should feel the same temp (hot). If the fan is switched on, one of the pipes (the return one) will feel just slightly cooler that the other one (supply). If the return pipe feels very much cooler, that suggests coolant flow through the matrix is slow/restricted/blocked. Normally coolant flow through the matrix (provided by the water pump) is quite brisk.
Chris
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Re: DS4 heating

Post by metalhead_79 »

The flow through the matrix must definitely be restricted in this case.
How do I go about getting rid of eventual air pockets before I get a new heater matrix?
Or maybe it is possible to get the old matrix unclogged?
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Re: DS4 heating

Post by GiveMeABreak »

Appreciate that the inlet pipe to the matrix always runs hot when the engine is up to temp Chris - I meant turning the cabin temperature to the coolest setting cold will prevent any heat from entering the cabin and so ensure the return pipe from the matrix is hotter - which will give a better indication. So if the matrix return pipe is still significantly cool, then it isn't circulating.
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Marc
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white exec
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Posts: 7445
Joined: 21 Dec 2015, 12:46
Location: Sayalonga, Malaga, Spain
My Cars: 1996 XM 2.5TD Exclusive hatch RHD
1992 BX19D Millesime hatch LHD
previously 1989 BX19RD, 1998 ZX 1.9D auto, 2001 Xantia 1.8i auto
and lots of Rovers before that: 1935 Ten, 1947 Sixteen, 1960 P5 3-litre, 1966 P6 2000, 1972 P6 2000TC, and 1975 P6B 3500S
x 1752

Re: DS4 heating

Post by white exec »

Agree with that, Marc.
Chris
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