W202 heating problem

[Spanial]

Well here goes a first thread.
Got a 1995 220 D, lots of miles but most things work but am confused on the heating.
Drivers side is cold whilst passengers is red hot, even with a cold day and both wheels up full in the red. Blower works all the time if you turn it on, got the buzzing from the light cluster, will do that.

Whats going on with it as 99% of the time it just blows cold air on the drivers side or on the screen, (very little to the screen tbh)

Confused!

 

[NW_Merc]

Could be the control unit is on its way out.......or possibly a loose connection

 

[stwat]

Does the 202 have a duo valve?

 

[Spanial]

Thanks for that.
Control unit, is that the actual dash head unit or a seperate unit elsewhere?
I did think it could have been just bad circulation so topped up the heating tank and on a recent trip to sunny London in heavy traffic the temp gauge hit the magic 100 deg, still ran fine but in order to cool it down we put the heater on and got hot air come through.
How badly would driving with the sunroof open affect the temp sensor.
Lots of questions I know but I've normally had climate control before so just set the temp and left it.

 

[nick mercedes]

Well here goes a first thread.
Got a 1995 220 D, lots of miles but most things work but am confused on the heating.
Drivers side is cold whilst passengers is red hot, even with a cold day and both wheels up full in the red. Blower works all the time if you turn it on, got the buzzing from the light cluster, will do that.

Whats going on with it as 99% of the time it just blows cold air on the drivers side or on the screen, (very little to the screen tbh)

Confused!

Have a look at the duo-valve (under the bonnet).

 

[NW_Merc]

The duo valve is under the bonnet, drivers side, near the back of the engine bay.

 

[horgantrevor]

yes the valves are were the brake master cylinder is and fuse box

you will see two what look like large battery's grey in color and they may be at fault one stuck open

they do give trouble

 

[Spanial]

Found them, bypassed like a christmas tree. The red wire on the left is going through a fuse and then to an earth point on the body.
Think it may be a new one, any idea on cost of these?

 

[horgantrevor]

man what a mess ill go a get a pic of mine in a while then try and wire it back to original this amy fix it

the light brown is an earth on mercedes

 

[horgantrevor]

i see one wire not connected that could be the prob ill be back with info hopefull a cheap fix

 

[horgantrevor]

hi i hope this helps

 

[Spanial]

Cheers bud, will have a go at it later and let you know what happens.

 

[Spanial]

Ok, having looked at another thread and taken the advice of horgentrevor I examined and then took the connector off the Duovalve and hey presto, full heat all round, so, problem with the valve then. I also touched the tops of the solenoids and they were red hot, even after just 1 minute of the engine running and still effectively cold.
Am I better off just replacing the whole valve, solenoids and all?

 

[Juls]

Good question... my SLK 230 is showing the same problem with the duovalves... Are they repairable or if they are hot and one side is blowing hot while the other blows cold is it just a replacement?

Juls.