W211 interior heating problem.

[NickPlymouth]

Hi all.

I have recently bought a 2004 E320 CDi and there is no heat coming into the cabin. Its the basic dual zone system. After an internet search, it seemed the problem would be the duo valve/heater shut off valve so this has been replaced with no effect.

The outside air temperature reading was miles off, so the sensor was replaced and I now get sensible readings, but no effect on interior heat.

I have tried an alternative control unit (including a digital one, but this makes no difference).

The fan operates as you would expect - if the interior is cold, but the engine is warm, the fan runs quite quickly.

What I have just noticed is that the air is always to the face vents and feet regardless of what the vents are set too. Nothing goes to the windscreen no matter what the setting is. I'm not convinced the aircon is working either although the a/c light does what I would expect.

Can anybody suggest what the issue(s) is/are? I presume they could all be related?

Apart from finding somebody with STAR, (difficult as car is SORN'd) is there a way I can do some diagnostics using the panel (I've tried holding REST for several seconds, AUTO+RECIRC, but they don't seem to do anything)? I thought there was a way to display some more information with the digital controller, but will it work if it is not original equipment?

TIA.

Nick.

 

[television]

Nick, what temp does the engine get up to, it should be near the 85 mark.

 

[NickPlymouth]

Nick, what temp does the engine get up to, it should be near the 85 mark.

Seems to be about 80 deg.

Nick.

 

[television]

Without STAR its not easy, is the circulation pump running 300, the pipes should be warm to hot leading to and coming from, if that is OK it must be a flap not working

 

[NickPlymouth]

Thanks television.
I'm going to have another look after Christmas and see what I can find them.
Nick.

 

[WG M-B]

Just to add. I think you may have more than one issue
I would be sure that the pipes on the back of the valve were fitted correctly when the new valve was installed
The motorised valve is driven by the front Sam and I know the driver can fail.
The directional issue with the vents is most likely a flap not moving as Malcolm already said

 

[NickPlymouth]

Right. I got the car warmed up and checked what was going on under the bonnet:

Pump (300) appears to be running.
Pipe (100) gets hot and so do the two running up to the bulk head.

I guess this points to the flaps inside not moving. As none of them seem to be working, is there something common that could cause this?

Thanks,
Nick.

 

[television]

This is odd , do the demist buttons and flaps work

 

[NickPlymouth]

This is odd , do the demist buttons and flaps work

The demist button lights up, and the fan speeds up, but no air comes out at the windscreen.

The top half of the dash was off recently, so I'm wondering if something has been disconnected (although I don't think so). Unfortunately, I don't know if it was all working before that or not.

Nick.

 

[television]

Ok then a non functioning heater box

 

[NickPlymouth]

Fixed: W211 interior heating problem.

Well, it turned out to be a lead not connected.

After taking the top half the dash off I found it. There are three wires into the back of the climate control unit.

1. The wires from the vents.
2. the wires that carry power and control the fan.
3. A flat cable with 3 wires that apparently controls the flaps.

The flat cable was not visible with the climate control unit removed as it had dropped down inside.

It all now appears to work ok.

Thanks for the help.

 

[NickPlymouth]

The attached photo shows the sockets.
Nick.

 

[television]

The attached photo shows the sockets.
Nick.

They do make a difference when plugged in