C4 1.6HDI - Auxiliary electric heater?

[uncle buck]

Buck - I think the relay is integral; there are 5 wires to the unit: power, earth, 2 command wires, and one from the BSI I am not sure of! Yes, there appear to be fuses under the plastic cover over the battery.

Thanks for that, will save me searching for a relay that it hasn't got
Looking at images of the C4 on google I see the bank of fuses you mention, they are normally clipped on top of the battery cover, this car doesn't have them in clipped on top so I'll take a look under the cover tomorrow.

The amazing thing is that all the cars were 15 years old and the aux heating still worked.
Have you actually checked the element to see if it is o/c because I have not known of one fail and one of the cars had done 246k miles.

Peter

No I haven't checked the element or anything yet, just trying to figure out how the thing works with regard to fuses etc, before I jump in.
Since we've had a few frosty mornings it's become noticeable just how long it takes before any warm air is available to help defrost the windscreen, I'm sure it never used to be this bad so that's my reason for suspecting there's something up with the heater.

I'll see what I can find tomorrow and let you all know.

Thanks for the help.



Cheers.

[Peter.N.]

If its working you should have warm air within about a minute of starting. My temperature gauge doesn't lift of the stop for a couple of miles but the heat output from the aux is good.

Peter

[uncle buck]

Yours sounds great, No I don't think ours does that, well so the wife tells me.

See what I can find...



Cheers.

[myglaren]

@ GiveMeABbreak,
Thanks for the info and the link, if it's broken it will definitely be a 2nd hand unit at those prices.

@ RichardW,
Can't say I've ever noticed any fuses on top of the battery, the battery is under a plastic cover, are the fuses under the cover?

Any idea where the relay will be?


I'm just gathering the info I need before I start fault finding why it's not working.



Cheers.

The fuse box is 'above' the battery in the sense that it is closer to the screen:

There is another fusebox under that one where the maxi-fuses are located. Thought I had a photo of that too but can't find it.

[RichardW]

No, that's not it Steve - on the C4 there is actually a set of fuses right on top of the battery!

[jgra1]

have that on the boxer I think... an odd flat box on the battery which is a terminal and some fuses.

[uncle buck]

I'm sure there are no fuses like that on top of the battery on our car, there is a normal plastic cover over the battery, so unless they are hidden under that?

I didn't get a chance to look at the car over the weekend as had some running about to do, will try to get a look at it in the next few days and report back.


Cheers.

[uncle buck]

Ok, looking at the car today, definitely no fuses on top of the battery like in Richards picture.

There is a fuse box next to the battery, this houses the ECU and also has standard and mini size fuses in it, there is also a row of maxi size fuses lower down but they are very difficult to get at, it looks like you would have to dismantle the fuse box to get to them. As far as I could see with my mirror and torch they all looked to be ok.

So onto the heating element, removed the kick panel and got the element out, the multi connector plug connections were in good condition as was the heating element, each connection of the element showed resistance when checked with the multimeter, so I assume the thing is ok.

Connected the element back up but left it out of the heater housing and started the car up, heat dial to max and fan on 2.
(The outside temperature was 13 degrees C)
After a couple of seconds I could feel the element getting hot, I got the IR thermometer pointed at it after about a minuter it was showing 50 (ish) degrees C right across the element, it may have got hotter if I had ran it for longer but I turned it off so I could put it back together.

So the element is working and heating up and as all of the fuses, connections etc. are in good condition I can only assume it's always been working, but if that's the case why is the heat output so poor?

Peter.N.
Is it likely that the 406 has a bigger higher output element fitted, hence the better heat?


I'll have to wait for a cold day to see if there is any difference in the heat output than before I touched it.


Will keep you posted.


Cheers.

[Hell Razor5543]

Have you changed the pollen filter? This can, if old, can restrict the airflow somewhat (read as completely block the airflow!).

[white exec]

Not sure how the C4 does it, but these electrical heating elements are often PTC (positive temperature coefficient), which means their resistance rises as they get hotter. This makes them 'self-regulating', as they can only get so hot and no more.

Again, not sure about C4, but it's common for the elements only to come on when
- heater control is wound up to maximum
- coolant temperature is below a certain figure (so they are inoperative with a warm engine)
This prevents unnecessary use of a current-hungry device (can be up to 30-40amp).

[uncle buck]

Hell Razor5543,
Yeah the pollen filter is ok and there is plenty of air flow.

white exec,
Yeah I understand the unit will only work when the coolant temp is below a certain level, the element was working today with the fan on 2 but will try it on max also.

I do know that when the car is covered with frost and we start it and put the heater on to clear the screen it's needs to stand for a good few minutes before there's the slightest signs of the screen frost starting to melt.
Also when driving from cold it takes at least about 1 mile before you notice the slightest change in the heat from the vents.

I think the fuse for this element is 70 amps if I'm correct.



Cheers.

[white exec]

Also when driving from cold it takes at least about 1 mile before you notice the slightest change in the heat from the vents.

That confirms the heater panel is definitely not working. The 1 mile of driving (assuming on the flat) is the coolant temperature rising, not the panel working.

Cold engine, heat set to a high setting (on many cars) - should produce some warmth from the vents within about 1 minute, and build to decent warmth (able to defrost) within 3-5 minutes, even when going downhill and consuming no fuel. That latter is the reason these PTC heaters are fitted to diesels, because they take 'for ever' to generate useful engine (coolant) warmth when burning little or no fuel.

I think you'll have to start chasing through the supply to pinpoint where it has failed. At least you know the panel itself is ok.

[Peter.N.]

Peter.N.
Is it likely that the 406 has a bigger higher output element fitted, hence the better heat?


I'll have to wait for a cold day to see if there is any difference in the heat output than before I touched it.


Will keep you posted.


Cheers.

I would think they are probably all the same, my C5 gave a similar sort of output. I didn't know the C5 had one until we were in Scotland one year, we had left the cottage and it was all down hill to the main road, the gauge was still planted firmly on the stop and yet I had quite a substantial amount of heat being delivered by the time we reached it.

Peter

[uncle buck]

Well I'm not sure what is going on with this heating element then.

I looked on the internet and the 406 elements I could find had a label showing a rating of 1000 watts, there were no marking as such on the label of this one, so no clues to it's output.

The plug that connects to it is in a position where there is no stress on it so not much chance of any breaks in the wires or anything, it definitely worked today when I tested it (connected to the car but not inside the heater housing) but when back together the heat from the vents was very poor, put it this way, if you didn't know it had a heating element you would have never of guessed.

Maybe I'm expecting too much, I'll try it from cold and use the IR thermometer to try to get a more accurate idea of the temperature of the air from the vents.

I could also maybe devise a way to temporarily clamp the coolant pipe that goes to the heater matrix so then I could confirm if the heat from the vents was from the element.

The weather forecast for the next few days is mild so not the best for testing the operation but I'll see what I can do.



Cheers.

[Peter.N.]

If you can measure the resistance it will be very low, possibly not measurable with a normal meter and connections, one ohm would be about 150 amps so 1kw should be about 0.15 ohms, very difficult to measure.

Peter