Need to disable heater in 300SDL
 

Greetings,

My old 300SDL running the heater at all times now, despite any wheel or button adjustment...it's driving me out of the car (I live in Southern Mexico). Is there a way to stop the heat without disconnecting the heater core? The AC hasn't worked for years and is not an issue.

Thanks.

Use a clamp to block off heater supply line.

is that the single rubber tube on the driver's side running thru the firewall?

Mono Valve is stuck open

is it possible to unstick the monovalve?

Just fix it... the rebuild kit is like $50 and is available on this site.

http://catalog.peachparts.com/ShopByVehicle.epc?q=&yearid=1987%40%401987&makeid=63%40%40MERCEDES+BENZ%40%40X&modelid=6213%3AED|100 00100%3AMBC|1512%40%40300SDL&keyword=mono&subcatid=P:242328@@Mono%20Valve%20Repair%20Kit&mode=PA

-J

Take it apart and inspect it - mine takes a manual adjust with a rubber hammer once a year. There are four screws on top (becareful don't drop into the sound wall cavern). Its very tight tollerance for a valve. Sometimes a little steel wool gets everything moving again.