’88 300E: Heater stays on all the time!

Hello All,

 

I just bought an 88 300E, and did a tune up.  After the tune up, my heater stays on all the time.  Through every vent, at max heat.  I am not sure where to start, but has anyone else had experience with this?  I am wondering if it is a vaccum leak, or a bad control unit?  Please help, and feel free to message me!

Thank you!

Mike

It must be a stuck heater valve. this is located beside the brake servo. you will see a coolant hose passing through small twin cylinders. call a local dealership and order a new one then fit it this will cure the problem. also check for blown fuses first.