W210 Heater Problems

[sidmon]

My '96 E420 with electronic climate control has a heater/duovalve problem. When I went to service my duovalve in January I noticed one of the plastic plungers was broken/snapped in half. After much enquiring I have managed to source a new plunger and yesterday replaced it. The heating is now quite cold unless Hi is selected and even then it's not blisteringly hot. What could have happened to have suddenly caused this, as before the new plunger was fitted it was warm!

 

[mattkh]

Hi
The plunger is moved by the electricity in the coils. Check the coils.

 

[sidmon]

Coils did have a little coolant on them when I took them apart, which I thought was strange.

 

[Parrot of Doom]

Default position for the duovalve to fail in is 'warm' (so you don't die of cold), I reckon you might be buying a new duovalve if the coils have had a soaking (corrosion)

 

[sidmon]

Theres no corrosion, just not too cold......are the plungers up or down when you want heat?

 

[Parrot of Doom]

Up I would imagine (to allow the flow of water) but tbh I don't know.

 

[liverbird]

normally when they fail its cold ive changed loads of duo valve for no heat

 

[len_merclover]

Default position for the duovalve to fail in is 'warm' (so you don't die of cold), I reckon you might be buying a new duovalve if the coils have had a soaking (corrosion)

if this is the case why's mine the opposite!?

 

[sidmon]

When chaging the duovalve (which I'm finally going to do!) can I keep the main base of the old duovalve to save me have to swap those bottom hoses over. It seems all the "gubbins" of the duovalve is on the top half.

 

[sidmon]

Managed to replace the duovalve today for a brand new genuine one but now I've got no heat from the climate control! These Mercedes H&V systems are beginning to annoy me!

 

[sidmon]

I'm going to use a blowtorch on it soon!