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Submitted by MercedesMedic on November 19, 2019
Mercedes Not Blowing Hot Air E-Class / CLS-Class

Mercedes-Benz vehicles such as E-Class W211 and CLS-Class  W218 may stop blowing hot or warm air even when the climate control settings are set to maximum heat. 

A defective Mercedes heater control valve often causes this problem.

To fix the problem, you will need to remove the heater control valve located in the engine bay by the firewall.


  • Mercedes not blowing hot air
  • A/C has no hot air
  • Climate control only blows cold air

How to replace Mercedes heater valve

What you will need


  1. Park vehicle and set the parking brakes.  
  2. Open the hood by pulling the hood release under the dashboard. 
  3. Remove the three 13 mm nuts that hold the windshield wipers in place. Remove the wiper arms by pulling them up.remove 13mm nut 
  4. Next, you need to remove the plastic trim. Before you do so, you need to remove the four small plastic screws.  Remove the plastic trim by pulling it up. remove plastic trim
  5. Remove the windshield wiper linkage. There are two 13 mm nuts and one 13 mm bolt that needs to be removed. remove bolt wiper linkageOnce the linkage bolts are removed, move the linkage assembly to the side. 
  6. Now you can access the heater control valve. mercedes heater control valave location
  7. Use needle-nose pliers to pull on the retainer clips. You don't need to remove the clips completely. disconnect heater valve hoses They need to be pulled out slightly. This will allow you to remove the hoses. Note that coolant may come out of the hoses. 
  8. Remove the clamp on the coolant hose on the left side of the heater valve. mercedes heater hose valve
  9. Disconnect the electrical connector. Remove the old heater valve and install a new one in reverse order. mercedes heater valve