Failed Digital Heater Control Valve May Cause Poor Heat Output on Mercedes-Benz E350 4MATIC

Problem Description and Possible Solution

A failed digital heater control valve can cause a lack of heat output from the climate control system.

Problem Data
RepairPal Verified
Average mileage: 75,581 (9,375–126,500)
6 model years affected: 2006, 2007, 2008, 2009, more2010, 2013
23 people reported this problem
Viewing 1 - 9 of 9 comments
Temperature reading is around 50 deg celsius. It should be around 80 deg C. Car does not heat up in cold weather.
The Heater Control Valve failed, stuck in the heat position.
Driver side SAM needed to be replaced because there was not enough current coming from the driver side of the car to start the AC Clutch.
The line that allows Freon to flow to the AC Compressor had collapsed.

I finally took the car to the dealer. Beyond a doubt Mercedes Benz installed a substandard AC/Heater System in my 2008 E350 4Matic.
Cold air comes out when heat is turned on. They said it was the heat sensor and the heat exchange motor. Later said it was something else.
Freezing cold inside-diagnosed at the dealer-replaced at local shop for less-$250
When cutting on my heat inside the car,at a sudden point a noise comes from the car vent, sound it makes it sound like a cricket.
heat readings is less than it should be i have yellow light check engine on

heats is not strong enough in the cabin
slow to produce heat in cabin, never gets what I would call hot.
No heat is coming out of the HVAC system, water temperature gauge is indicating <50 degrees celsius, should be around 80+
Car not heating up except for when put in max