CLK220 Cabin heater blender flap/motor not working

barnaclebill15

Senior Member
Joined
Mar 24, 2015
Messages
297
Reaction score
94
Location
newcastle upon tyne
Your Mercedes
clk220cdi/2006/diesel
In this cold weather I have noticed the air from the cabin vents is tepid at best even with engine temp at 88C. The cabin vents work ok and cycle when you try reset.
The best thing I can do is leave system in manual and turn both heater knobs to max and set the fan to a low setting then it will slowly get a little warm, if I leave it in auto the fan will go to high speed as it detects a cold cabin but you get more cold air than warm
I presume the resetting of the cabin flaps does not include the blender flap?
I do not think it's a blocked heater as when I first got this car if I wanted to make it a little warmer and set both temp controls up one or two clicks when in auto it would go to high speed fan and very hot then go to low speed and the AC would kick in for a few seconds cooling so I used to leave the temp setting on the mid point 22 and it would work ok warmish in winter and give some cold air in summer ( if it got hot up here in the north).
I suspect the blender flap/actuator motor system, can this be checked on STAR and can it be moved by STAR? If not it will be a dashboard out job
 

Oldspanners

Senior Member
Joined
Oct 30, 2017
Messages
1,487
Reaction score
1,598
Location
Normandy
Your Mercedes
C CLASS 2004 C180
In this cold weather I have noticed the air from the cabin vents is tepid at best even with engine temp at 88C. The cabin vents work ok and cycle when you try reset.
The best thing I can do is leave system in manual and turn both heater knobs to max and set the fan to a low setting then it will slowly get a little warm, if I leave it in auto the fan will go to high speed as it detects a cold cabin but you get more cold air than warm
I presume the resetting of the cabin flaps does not include the blender flap?
I do not think it's a blocked heater as when I first got this car if I wanted to make it a little warmer and set both temp controls up one or two clicks when in auto it would go to high speed fan and very hot then go to low speed and the AC would kick in for a few seconds cooling so I used to leave the temp setting on the mid point 22 and it would work ok warmish in winter and give some cold air in summer ( if it got hot up here in the north).
I suspect the blender flap/actuator motor system, can this be checked on STAR and can it be moved by STAR? If not it will be a dashboard out job
Are you getting any clicking sounds from behind the dash when you first switch the ignition on?
If so it's probably either the heater flap operating arm or the motor gearing.
 
OP
barnaclebill15

barnaclebill15

Senior Member
Joined
Mar 24, 2015
Messages
297
Reaction score
94
Location
newcastle upon tyne
Your Mercedes
clk220cdi/2006/diesel
  • Thread Starter
  • Thread starter
  • #3
there are no clicks behind the dash at switch on and all the direction flaps work well
 

Uncle Benz

Senior Member
Joined
Mar 31, 2006
Messages
4,220
Reaction score
3,548
Age
53
Location
West Sussex
Your Mercedes
Mainly Mercedes
There are separate blend motors for each side, so if both sides are cold it is unlikely that both motors have failed at the same time. I have replaced a few faulty blend motors, and it's usually one side that doesn't work. I think a normalisation and test via star first, a check that the temperature sensors are reading correctly and a check for blocked matrix would be a wise start.

Engine thermostat a possibility too.
 
OP
barnaclebill15

barnaclebill15

Senior Member
Joined
Mar 24, 2015
Messages
297
Reaction score
94
Location
newcastle upon tyne
Your Mercedes
clk220cdi/2006/diesel
  • Thread Starter
  • Thread starter
  • #5
Thanks for that uncle benz, it's logical it needs two and unlikely both are faulty, thermostat is ok as it gets up to 88C in 3 or 4 miles and holds so it's a STAR check next, it's booked in for a service at my indie soon so I'll add that
 


Welwyn Merx Limited is a family run business with genuine passion, dedication and 25 years of experience dealing with Mercedes-Benz and AMG passenger cars.
Tel: 01707 395999www.welwynmerx.uk
Top Bottom