Heater Controls...what am I missing?

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seanlandy

seanlandy

Active Member
Posts
286
Location
Cannock
Having plumbed in a new heater matrix on my 90 and reconnected the control cables as they were, I was surprised to find that when I move the inner of the two control levers, there was no corresponding movement on the side heater arm. the outer, lever for the temp, moves the top one as I assume it should. On further investigation the inner lever seems to work the flap that operates just above the passenger side footwell. So where is the lever that operates the arm on the side of the heater unit, or should it work in tandem with the other one.
Most perplexing. Can someone please shed some light on this, as I am baffled at the moment. Thanks
 
One of the RH levers controls the mixer-flap on the heater-box and gives temperature control. The other one operates the air-flow direction / demist flap in the lower dash and does not connect to the heater-box at all.
The LH lever controls the fan electrical operation (On / Off + Speed) plus also the flap that shuts off air-flow through the heater-box.

Sounds to me like you have connected the cables incorrectly.
 
Right cheers. A photo would be handy. I did just reconnect as they were connected but I guess one shouldn't always assume they were correct. I realise the fan is the left control, but are you saying that this also operates the lever on the side of the heater unit? That may make some sense.
 
Have a look in the rave workshop manual, ( download above ) it explains it really well.

I will take a piccie tomorrow of the heater box and the fixing.

Cheers
 
seanlandy said:
Right cheers. A photo would be handy. I did just reconnect as they were connected but I guess one shouldn't always assume they were correct. I realise the fan is the left control, but are you saying that this also operates the lever on the side of the heater unit? That may make some sense.
Click to expand...
It really isn't that complex tbh...

There are only 3 heater controls:

1. Fan speed
2. Direction
3. Hot or cold

The direction control obviously has nothing to do with the actual heater, as it directs air either at the screen or your feet. You can hear and feel a clonk when you change this, which gives you a good idea where it might be connected ;)

Fan speed is obviously a switch that controls the speed of the motor fan....

So last up is Hot or cold. This couldn't be more simple. A heater works like a radiator. I.e. there is a rad looking thing called a heater matrix, hot water flows through this. And the fan blows air over/through it. And a heat exchange happens, where some heat is taken out of the water and makes the air hotter.

To stop it heating the air you simply stop the supply of hot water. So there will be a physical valve that is attached to one of the levers.

:)
 
300bhp/ton said:
It really isn't that complex tbh...

There are only 3 heater controls:

1. Fan speed
2. Direction
3. Hot or cold

The direction control obviously has nothing to do with the actual heater, as it directs air either at the screen or your feet. You can hear and feel a clonk when you change this, which gives you a good idea where it might be connected ;)

Fan speed is obviously a switch that controls the speed of the motor fan....

So last up is Hot or cold. This couldn't be more simple. A heater works like a radiator. I.e. there is a rad looking thing called a heater matrix, hot water flows through this. And the fan blows air over/through it. And a heat exchange happens, where some heat is taken out of the water and makes the air hotter.

To stop it heating the air you simply stop the supply of hot water. So there will be a physical valve that is attached to one of the levers.

:)
Click to expand...

So the hot water supply flow is stopped?
 
neilly said:
So the hot water supply flow is stopped?
Click to expand...

http://www.roversnorth.com/Land-Rover-Parts/141
upload_2016-9-20_12-47-3.png
 
@Dippypud

see the quote from @300bhp/ton , he states .

300bhp/ton said:
To stop it heating the air you simply stop the supply of hot water. So there will be a physical valve that is attached to one of the levers.
Click to expand...

Which from my POV is wrong as you do not stop the supply of hot water you simply stop the air flow through the heater matrx from going into the cab. Which I find funny because he states at the beginning .

300bhp/ton said:
It really isn't that complex tbh...
Click to expand...

:rolleyes::D


Anyway,
 
Last edited:
neilly said:
@Dippypud

see the quote from @300bhp/ton , he states .



Which from my POV is wrong as you do not stop the supply of hot water you simply stop the air flow through the heater matrx from going into the cabinet. Which I find funny because he states at the beginning .



:rolleyes::D


Anyway,
Click to expand...

The thought of that water flow stopping strikes fear in my heart ....

and the H/G ...

it is diversion of heat ...from the cabin to not ...
 
IMG_0329.JPG IMG_0330.JPG

the image showing the side of the heaterbox shows the cable connection for the heater fan control ( LH lever)
the image which shows the connection on the top of the heater cabinet, shows the cable connected to the temperature control lever.

Cheers
 
Thanks for that. I think mine are correct. I understood the principal even though it doesn't have a rudimentary heater bypass to cut off the water. Even an old mini had this, I recall. What I hadn't realised is that the fan switch doubles up as a lever. I should have guessed by the mechanical nature of its movement. I shall have a play and try and adjust accurately. Cheers.. For now....
 
There is no valve to cut off the water it circulates all the time, I've had mine apart and unless they have done something funky on the newer ones thats how it works.

I replaced my heating matrix, and it made no difference to the old one I had in, its still crap, aparently this is a feature of pre TD5 defenders. I did see one however that did work Flatdog's was very impresses with that.
 
It's made me go out and look at mine to check too. Yes, as I suspected, I don't have a valve on the water circuit (although some cars do of course). The controls just move flaps to direct the air over the heater matrix or not, or through the pipes to the footwells or up to the screen.
 
SpaceDawg said:
There is no valve to cut off the water it circulates all the time, I've had mine apart and unless they have done something funky on the newer ones thats how it works.

I replaced my heating matrix, and it made no difference to the old one I had in, its still crap, aparently this is a feature of pre TD5 defenders. I did see one however that did work Flatdog's was very impresses with that.
Click to expand...

The main thing, (there's a write -up somewhere on here), is to sort out the seals and insulation, the old foam is fubt about now ...
 
To stop it heating the air you simply stop the supply of hot water. So there will be a physical valve that is attached to one of the levers.
:)


Well, that's not really correct is it!
The LH lever operates the electrical side of things but also (via a cable) the main flap in the heater-box that stops all air-flow through the heater into the cab. The is no interruption to the water supply so the matrix will be hot regardless of the lever settings.

The heater on these vehicles is as you say, simplicity itself but even moreso than you presume.
For heater temp output there is a flap in the heater-box that directs incoming air either through or around the matrix (through for full heat and around for cold), a midpoint setting means there is a mixture of heated & unheated air hence the variation of temperature.
To shut-off the flow of air through the heater-box completely the LH lever is raised to the top, this closes the flap on the heater-outlet and means that there is no natural through-flow of air when the vehicle is moving which would otherwise happen even with the blower off.


It is the sealing of these flaps and adjustment of the cables that makes all the difference to the performance of a Defender heater.
As long as your cooling system is working as it should then the same coolant will be flowing through the matrix and therefore the same heat will be available, the trick is to get this through into the cab and a few minutes setting the cables correctly can make a massive difference.
 
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