Fountain35

I have been driving this past summer with A/C or the windows down. I turned on the heater two days ago and got cool air out of the vents when the temperature set on "HI" heat. I shut the car off, ate dinner came out and bingo I had heat. Today I started the car drove it for 30 minutes and no heat, cool air. Shut the car off came back 40 minutes later and heat. Could this be that valve under the windshield that is going south?

Thanks,
Chris

machild

Added: I just realized you have an E class not a CLS. The under hood layout is the same thou.
For heating there are two main components you should confirm are functioing. A circulation pump and a control valve. For the control valve there is one hot engine coolant hose going in and two that comes out. Check you have warm/hot going in and warm/hot coming out when set on a high interior heat setting. The attachement is the part view of the under hood layout. Item 30 is the control valve and item 300 is the pump. There are other things that can cause your issue, but these are the most likely suspects.

Fountain35

Thank you! Ordered the control valve and a new blower motor/resister/cabin filter while I was at it.