Xantia heater

[froggy]

Hi, my series 1 Xantia . The heater is only blowing luke warm air and not hot air . Do I need to replace the thermastat ?
cheers Terry .

[spider]

Where is the temperature gauge sat during normal running / driving ?

The thermostat is one thing, it might just be airlocked (in just the heater) , another less likely possibility is the heater control cable / flap is not operating properly.

Thermostat is a good place to start though, I'd be tempted to change it if in doubt anyway as you'll be able to flush out and have to bleed the system while you're at it.

If you wanted a 'no cost' test, rebleed the coolant system, at minimum the heater valve (I'm assuming its the same as a 406 in that there's a tyre valve type cap fitted on one hose up by the bulkhead, usually about out of sight)

[CitroJim]

If a bleed did not help, does the heater start off lovely and hot and then cool right off?

Does the car have aircon?

[froggy]

The engine runs just a fraction under 80 degrees, but the heater starts cold and only reaches luke warm Jim .
many thanks Terry .

[CitroJim]

No worries Terry, it's just there is a known issue with the cabin temperature sensor that will cause the gheater to start off hot and then cool right off due to the little fan in the sensor seizing and stopping airflow over it. It ends up reading the under-dash temperature, which is hot! and decides that the cabin is too hot and cools it off...

Are the pipes going to the matrix nice and hot?

[froggy]

Hi Jim , the pipes going to the matrix are only warm . thanks Terry

[citroenxm]

If the pipes to the heater are only luke warm then theres a flow problem if your temp is reading "Normal" which under 80 deg is about right..

Whats the "Anti Freeze" history like?? Lack of, or correct amount?? Or not enough? Is the water Brown with rust??

Am asking as there could be a restriction at the head gasket of water flow.. Water direction is from the block through the head gasket then out the back of the head - I have seen many a head gasket with the water ways bunged up with "rusty" particles from rusty water due to lack of no anti freeze.. Unfortunally, as the block is cast it will and does rust with water, so a strong mix of anti freeze with "Anti Rust" hibitors in it is needed essentially to prevent the restriction..

Paul

[froggy]

Hi, the antifreeze I change every two years and I"ve changed it this summer . many thanks Terry.

[CitroJim]

Are you sure it's 100% properly bled Terry?

Don't for get you need to bleed the matrix via the tyre valve cap on the matrix elbow connector. If you don't do this at coolant change time you'll surely have an airlock in the matrix.

[froggy]

Thanks Jim , I will let you know . cheers Terry .

[aneesh84]

Hi my citroen mk1 heater does not blow hot enough air. The engine temperature remains between 70 and 80 degrees. Sometimes when i just start the fan it gets hot but immediately cools off. It may be the sensor issue as mentioned in a previous post. But however this happens even when i turn the temperature knob all the way till red. From my understanding at this setting the hot air should blow at max irrespective of the temperature sensed. Can you guide me where is the hot/cold flap located so that i can see its position.

[Clogzz]

The temperature slider on red causes slow fan speed to have the hottest possible air.
Looks like the temperature sensor, maybe first try blowing into it with a short tube.
The hot air flap can’t be seen or reached, it’s buried in the works and operated by a motor tucked under the very front of the passenger’s side of the centre console.
That’s all assuming that it’s an air-conditioned car because normal heating wouldn’t cool off that fast.

[aneesh84]

No my point was this that if i put the temperature slider on extreme red, should it not override the temperature sensor, because that means i am not asking it to regulate any temperature but rather blow at maximum heat.

[CitroJim]

No my point was this that if i put the temperature slider on extreme red, should it not override the temperature sensor, because that means i am not asking it to regulate any temperature but rather blow at maximum heat.

That is indeed true. In fact, from cold the flap will be in the full hot position and it will move gradually cooler as the sensors detect heat.

The flap is motor driven and with the motor in place with its reduction gearbox it is almost impossible to see where the flap is. You may be able to see the flap extension arm (there for non-AC cars to attach a control cable to) if you squint past the motor shown in Clogzz's post with a mirror but you'll be lucky. If you can, the end of the arm will face toward the front of the car when in the fully hot position. It arcs around roughly 6o degrees between cold and hot.

This picture of an early MK1 heater box upside-down and removed from a car for clarity helps to show there the extension arm is. It is shown in the fully hot position here...



Have you checked the water pipes to the matrix are getting nice and hot? More often than not, a cool heater is caused by either by an air lock in the matrix pipes, a silted-up matrix or inadequate airflow caused by leaves in the intake or a blocked pollen filter. The flap itself is usually fairly reliable.

[aneesh84]

Thanks citrojim. I could not see the picture of the heater in your post.

Also can you explain where exactly the input line to heater matrix is, so that i can feel the temperature. Or any picture that you can show me for the same. Do i have to go under the bonnet to reach it?