Heater Controls

[murramor]

On my car the heater control valve is in the front compartment.  The lower lever on the dash, which controls the water valve, was completely unmovable so I have changed the damaged cable between it and the water valve.  The lever now moves for about half its designated travel but the other cable on the valve seems very stiff.  The second cable that I am talking about, goes from the water valve through the bulkhead and presumably controls something on the heater box itself.  In my limited experience, I have never seen a similar arrangement with two cables on the water valve and I wonder what the second cable does and whether it can be freed up without removing the whole heater box.
regards
Ron, Sydney

[speed pete]

the seconde cable controlls a little valve at the heater to prevent cold air coming in to the interiorin winter

[murramor]

If that, indeed, is all it does then does anyone have an opinion as to whether I can simply delete it?  We don't have much of a Winter here and I usually drive my modern cars with the aircon on in Winter anyway!

[suffolkpete]

You can delete it, but they often seize and can easily be freed with a little penetrating oil at each end of the spindle, so why not do this and keep it as standard.

[murramor]

"can easily be freed with a little penetrating oil at each end of the spindle" 

Pete, are you saying that these spindles are easily accessible without removing the heater unit?  I find access under the dash very difficult due to an unusual medical condition that gives me severe vertigo when I try to fit under there so I have been working by feel.  A picture or schematic of the heater would be useful if anybody has one.  I am wondering if there is something in the parts manual which shows the various moving parts?

[roy4matra]

the seconde cable controlls a little valve at the heater to prevent cold air coming in to the interior in winter

Not quite right.  The outer cable connected to the tap opens and closes it, but also moves a second cable that goes directly back through the bulkhead to a flap in the heater box.  Old heater systems used the tap to control the hot coolant through the matrix, to adjust the temperature in the car.  Modern cars have hot coolant going through the matrix all the time and use flaps to control the temperature in the car (either blocking the hot air flow from the matrix or blocking the cold air coming in directly from outside) and these are called air blending systems.

The Murena is a combination of varying the coolant and air blending!  So you need both working.  I would not dispense with the link to the flap.

All this has been in the FAQs on my website for years - it is on the seventh page, and discusses how to turn off the tap fully to get cool air inside.

I suppose if your climate is hot all year round and you NEVER need the heater at any time, you could dispense with the coolant through the matrix altogether, by joining the two pipes or hoses together and by-passing the matrix.  But if you need the heater any time even if only for a small amount, that is not an option.  Also there is one other point here.  You might need the heater matrix to increase the overall cooling capacity slightly - but have the matrix under the front so the hot air doesn't heat the cabin!

Roy

[murramor]

Thanks Roy.  Now you mention it, I had read this section of your FAQ's several years ago but the old brain had completely forgotten it!  It just shows that a complete re-reading should be done at regular intervals.

The question remains, however, is it possible to free up the flap in the heater box without removing the heater box entirely which looks like quite a daunting job given my problem with working under the dash?

[roy4matra]

... We don't have much of a Winter here and I usually drive my modern cars with the aircon on in Winter anyway!

Just to clarify point this for many other car owners and people generally.  Using air con. in a car at any time can be advantageous whether winter or summer and whether in a temperate climate or a hot climate.  Air con. is not refrigeration as many think - it is air conditioning which is different.  I know many people who only think of air con. to cool the interior, but that is not the case.  In winter here in the U.K. and other places where it is cold, you can use air con. with the heater on which might sound contradictory IF you only think of the air con. as refrigeration.  But air con. is brilliant at changing the humidity so it gets rid of moisture condensed on the glass far quicker than waiting for enough heat from the engine to dry it off, so it clears the misting up you get on a cold day, which hinders you seeing out, and within 30 seconds usually!

We used to get customers in all the time, who had cars with air con. for the first time, and since they never read the hand books any more had never used their air con. except in summer for cooling; and didn't realise it was brilliant in winter too.

I understand that in your case Ron, it is used more for cooling in a hot climate, and you probably have little need for clearing misting of screens or other glass, but I wanted to clarify this as there are many who do not truly appreciate the air con. in modern cars.

Roy

[roy4matra]

Thanks Roy.  Now you mention it, I had read this section of your FAQ's several years ago but the old brain had completely forgotten it!  It just shows that a complete re-reading should be done at regular intervals.

The question remains, however, is it possible to free up the flap in the heater box without removing the heater box entirely which looks like quite a daunting job given my problem with working under the dash?

It is a while since I last took out a heater box on a Murena, but on a standard car, without any extra fittings like audio systems that may be in the way, it is not that difficult to remove, particularly unlike most modern cars where it is buried in the car and involves stripping the whole of the dash board.

But before you even think of removing the heater box assembly, you should check out the cable connections on the sides of the casing.  You can adjust or disconnect the cables on either side.  In fact you would need to disconnect these first to remove the heater assembly anyway!  So it may be your cable back to the heater flap is incorrectly connected, or the cable is kinked preventing full movement.  Or if the flap is stuck or jammed for some reason, it may be you could simply disconnect that cable, at least temporarily, to allow the full heater control movement of the tap.  But it might be the tap that is jamming part way - have you checked that it does move freely from full open to full close?  Is the seal inside still good enough to seal when fully closed?  Because others have perished and even when fully closed do not seal any longer and therefore still allow coolant through which still means some heat in the cabin.

And if the flap is stuck because something is jamming it, I would want to know what and rectify it before it can cause some other damage.

Roy

[murramor]

Roy, I have had the water tap off for cleaning and painting and it moves freely as do the controls for the flaps which direct air to the windscreen and feet (ie. the upper 2 levers on the dash move freely). The cable from the lowest lever to the water tap was definitely un-serviceable as the sheath of spiral wound metal and the inner cable had rusted together. It was replaced with a new nylon sheath cable from Simon.

The only problem now is the air blender cable which disappears from behind the tap into the heater box.  The cable has a nylon sheath and these don't seem to be prone to jamming so I conclude that the blender flap itself is the culprit.  While I could disconnect this cable and have the heater lever move freely on the dash and this would, indeed, not be much of a problem in our warm climate, I would prefer to have everything work as smoothly as the original design will allow.

By the way, re air-conditioning.  In my modern cars the aircon is never switched off even in the depths of our Winter which sometimes falls as low as 5 degrees C overnight!  As you correctly point out it provides almost instant demisting.

[MatraIan]

Hello Ron.
Coincidentally I have just removed my heater box this last weekend. It was working but slightly stiff on the cables, and as I am replacing all pipes and hoses with new and have had the engine cleaned ultrasonically I thought I would do the last piece of the puzzle and clean it out and make sure any dirty residue was not washed back in to the system.
I had released the 4 nuts holding it to the bulkhead and the front compartment hoses inc. tap. (I have cleaned and lubricated the tap and it now moves freely.)  This did involve lying on the floor of the car on my back so perhaps tricky for you. Once the vents were removed and the fixing behind the astray/vents it was a relatively easy. As Roy pointed out it is quite easy but mine was made awkward having to jiggle it around the extra quad amp that had been fitted by previous owner.

I could have flushed the matrix out whilst in the car but am glad I removed it for several reasons.
One is, that in car flush would not have got rid of the dried lumpy dirt chunks that finally came out after several hot water soaks and drying out.
Two, the matrix had a section of small leaves blocking air flow but was also blocked just as much by disintegrating foam from around the matrix and a poor foam seal to the bulkhead above the box. It had been there over 35 years.!
Three, it was easier to get to spindles to lubricate. They were all moving but now move with less effort.
NOTE: there is one of the three plates where one end of the spindle does not come out of the side casing and is on a bracket so cannot be lubricated without removing the heater box. Also the solid cable can be lubricated from the top and let go through the plastic casing.
As it is off the car I will post a couple of pics when I get back home.
Now need to clean up box casing which was in surprisingly good condition, get new foam and refit.
You could try lubricating the spindle ends you can get at and working back and forth and down the white casing on the solid tap cable, perhaps with cables disconnected at box end. It is worth trying in order to keep full functionality. Failing that you need a willing volunteer to assist in removal and, as I hope to have, when trying to re-fit.
For me it was worth the effort but we have different weather to you back here.!
Ian

[murramor]

Thanks Ian.  I would love to see some photos.  Like you, my engine has been rebuilt and the entire cooling system is new except for the heater so I am now very motivated to clean out this last piece of the puzzle.  The car was not run for 17 years so the coolant had turned into some sort of crystalline muck and I shudder to think what's inside the heater matrix!

Luckily, I have no radio fitted so access might be easier and I do have a couple of options for help which I will now explore.

regards
Ron

[MatraIan]

Hi Ron - 2 pictures attached
It is obvious where the pivot is on one end as that is where the cables connect the 2nd pic has the pivot points shown by red arrow. One is through a bracket inside and does not protrude through to the outer casing. You can also see how poor the foam is. The foam supports the matrix and seals the gaps between the different air routes inside. You can see the actual matrix which is in good condition now all the debris is cleaned off. The matrix sits in the top at an angle and is released by bending the two metal strips up, which hold it at the back and removing two rivets and a small plate that hold it at the front (not shown in pic). I said 4 nuts to remove there are 3 on top to bulkhead and one on a bracket at side of radio after removing vents.
Hope this helps.
Ian

[murramor]

Thanks Ian. That is very helpful. One further question. How does one take the ashtray out? The answer is probably simple but not obvious to me!
Thanks again.
Ron

[TELBOY]

Hi Ron,
I can help you with that one because I have experience in how not to do it!
The ashtray has a small clip at the back which is designed so it cannot be slid completely out without probable damage.
Slide it as far out as it will go, reach behind it and remove the three screws and the two nuts.
It comes out by moving the rear downwards and then the tabs at the front come away from the dash. The whole assembly comes out as one. don't forget to disconnect the wires for lighter and light.