Xantia MK1 freezing hot air

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ohms
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Xantia MK1 freezing hot air

Post by ohms »

Hi all,

Xantia MK1 with air con and it just never gets hot. Even when full temp selected on the slider. it gets warm blowing on the screen for a short amount of time and then blows cold. You can get mildly warm from the main vents but that's about it. The air con works a treat on cold, but no hot...help, it's freezing!!
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Post by jgra1 »

hi Ohms...

I had this with a 306TD and a 406 petrol

the 306 seems to have a blocked heater matrix/core, so not much water goes through it, it just comes straight back out again.. bad water used in the past I suspect have caused this

on the 406 it seemed to be caused by an airlock in the matrix, and some careful bleeding got things warm again..

check the level of coolant in the system too, low means the matrix will be the first to be empty I think, causing what you describe

finally, the flap that blows air over the matrix or not, could be broken etc, meaning you will never get much air through the matrix and therefore warm

check the two pipes that go from engine inside car, they should both be hot when egnie has ran for a while


Others will have more
:)
John
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Post by citroenxm »

When the engine is up to temperture.. check the heater pipes that go into the bulkhead to feed the heater and see how hot they are...

Unfortunally, either a blocked matrix or worse a SURE sign your head gasket is getting gummed up with Rust in the cooling ways in the gasket...

What happens is the flow of water runs up the block at the gearbox end, through the head gasket and then out the back of the cylinder head to the feed side of the heater in the car... it then goes through the heater and out the other side and DOWN to the lower joint on the back of the block...

A GOOD head gasket and unblocked matrix WILL and should start giving you heat BEFORE the needle has even started moving off the guage!

A bad Gasket will allow the warm water through to the heater but NOT enough of it to flow to give out any heat..

Lack of anti freeze in a Cast block = Rust.. As the rusty water passes through the gasket, the rusty particles BUILD UP on the edges of the Gasket then eventually closing the water ways up and restricing water flow!

Another sign is a slightly High Temperture reading on the guage which can also suddenly drop too..

EITHER job can be big if the matrix has to be removed HOWEVER, if you remove the heater feed pipes, which can be tricky and if brittle break, you could TRY reverse flushing the matrix to clear that out - completely DRAIN and POWER flush the cooling system.. then this will rule out the matrix and clear the exsistingrusty water - UNFORTUNALLY though this will not clear up the blocking gasket.. which can only be a head off job :? :(

IF you cannot get the heater pipes off at the bulkhead, take one off the cylinder head, and take the other off the lower join on the back of the engine... and power flush...

Good luck

Paul
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Post by Old-Guy »

I think a bit of systematic diagnosis is required (please forgive the obvious questions, but we can all ignore them!): -

1. Is the header tank full?

2. When the engine is hot, do both the heater pipes get really hot? If not, there's a blockage or an air lock.

If there's really is briefly some warm air when the fan is first switched on (and the engine is at least warm), it suggests that the air flap is working but that little heat is reaching the matrix; so air lock or blocked matrix.

My money's on an air lock. There's a post (CitroJim?) on changing coolant and bleeding. Easy enough if you follow the advice, but it's essential to do it properly with the engine up to temperature for the final stage (otherwise air gets trapped in the thermostat housing).

Best of luck

Guy
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Post by ohms »

Coolant system flushed, new thermostat and new anti-freeze added. Absolutely no rust or gunk or rubbish in the system anywhere. Was like new infact. It doesn't use any water whatsoever and I bled the system properly by pressurising via the header tank and bleeding it off, there is no air lock. No head gasket failure either, in fact mechanically the xant is like new in every way. Could have something to do with a FSH and only 75K miles when purchased.

:wink:

The car has climate control, which changes everything so far as I can see. I have no idea what extra gubbins is involved with this, in the way of sensors etc, but I have a feeling the fault les herein.

Anybody have experience of climate controlled xant heating problems? :D

Thanks chaps
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Post by jgra1 »

hi again Ohms

if you slide the heat full on and the fan full on that erradicates the climate control and puts everything in manual, at least its supposed to..
Climate only works on the auto setting...

?
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Post by citroenxm »

ohms wrote:Coolant system flushed, new thermostat and new anti-freeze added. Absolutely no rust or gunk or rubbish in the system anywhere. Was like new infact. It doesn't use any water whatsoever and I bled the system properly by pressurising via the header tank and bleeding it off, there is no air lock. No head gasket failure either, in fact mechanically the xant is like new in every way. Could have something to do with a FSH and only 75K miles when purchased.

:wink:

The car has climate control, which changes everything so far as I can see. I have no idea what extra gubbins is involved with this, in the way of sensors etc, but I have a feeling the fault les herein.

Anybody have experience of climate controlled xant heating problems? :D

Thanks chaps

Thats VERY good news then, it has to be flap or matrix related then!..

Good luck with yur quest!

Rgds
paul
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Post by CitroJim »

This sounds very much like the flap across the matrix compartment is stuck or not moving. It's motor driven and not unknown for it to give probelms mechanically. I'm sure there are a few posts covering this in on here.

There are also sensors and quite a few of them too. If one was lying and saying the cabin is boiling hot that will keep the flap closed. Te usual culprit is the cabin temperature sensor behind the grille containing the alarm LED. This has a little fan to draw air over the sensor and if this fan stops, the sensor reads stagnant hot air under the dash and keeps things very cold. However, as said, if you push the slider to full hot, the sensors are generally ignored. generally though, an unhappy cabin sensor will allow hot air for a bit and then cool everything down.

Is your blower running? Silly question perhaps but if it's not, you'll feel very little hot air as it's vital for airflow through the heater assembly. The same will if the pollen filter is totally blocked.

A quick run-through on a Lexia will check the sensors and also exercise the motor-driven flaps. Off-times, if it's a mechanical problem, you can hear the motor trying to drive the flaps.

I hope you can resolve this without removing the dash but if you have to, an ideal time to carry out a precautionary replacement of the matrix...
Jim

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Post by Clogzz »

experience of climate controlled xant
If both heater hoses are equally hot, we’re left to check for hot air flow, and temperature sensing.
The air-conditioned car has a motorised flap to control the flow of hot air from the matrix.
Flap motor faults are rare; the XM used to break the plastic drive cog.
The flap motor is at the very front bottom of the centre console, on the passenger’s side.

The cabin air temperature sensor fan can be seen by shining a light into the sensor grill.
When turning the key to ‘ignition’, even without starting, the fan spins a few turns clockwise.
It then stops, and restarts going anti-clockwise, to spin until the ignition is turned off.

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