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Heating not working CLK200 2007

grantmackay80

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Joined
May 20, 2010
Messages
56
Hi there, the heating in my Clk200 2007 isn’t working properly. It blows as it should but you only get slightly warm air coming out. I have tried the reset by pressing the demist and recirculate buttons together and it goes through the cycle but still no hot air. The air con doesn’t work which I assume needs recharged but maybe linked? The engine temperature gauge doesn’t work properly so not sure if this is related? It reads about 40 usually and never gets above 60. Any help would be appreciated. Thank G
 
Are you sure the gauge isn't working properly, or are you assuming its not working as it doesn't show it hot? Judging by what you have said i would say thermostat is stuck open and not allowing the engine to get up to temperature.
 
Thanks for your reply. That’s sounds possible. When I start the car from cold the temperature reads no more than 40 and it takes quite a while to get there. If I stop at the shop or something, when I turn the car back on the temperature is higher, usually about 60. So the thermostat could be at fault? Let me know what you think please. Cheers G
 
That does sound like thermostat to me. The temp being higher when you start up again could be heat soak from the engine as the water stops circulating. As soon as you start up the water gets pumped round and through the rad and cooled again. Mines usually sits at about 90 deg
 
Thanks for your input. The car also kind of gurgles when you first start up sometimes, sounds like water bubbling or moving at least behind the dash board. I will try replacing it.
 
My CLK sat at 90C all the time and the heater was always hot. Everything points to your thermostat.
 
99% sure its the thermostat. Not sure what the gurgling is, maybe its just the water circulating. At least you know the water pump is fine!
 
I doubt it, not sure why you think it would?

A CEL light will often trigger if coolant temperature is too low after a certain period of running. I had this on a Saab and the fault recorded was "Implausible coolant temperature"
 
A CEL light will often trigger if coolant temperature is too low after a certain period of running. I had this on a Saab and the fault recorded was "Implausible coolant temperature"
Never happened on my CLK when I had to replace the thermostat. A low coolant light came on at another time, but never the engine management light.
 
Other possibilities would be a failure of the duo valve which controls the flow of water thro the dash heater heat exchange radiators or the electric auxilliary coolant circulation pump if the car has one. If th engine itself is running cold it points to an engine thermostat problem as already suggested
 
Never happened on my CLK when I had to replace the thermostat. A low coolant light came on at another time, but never the engine management light.

Perhaps MB do not flag this on some models but regardless a CEL can be triggered by a failing thermostat, it may look at fueling values / engine temperature/ time since start etc to determine that there is a problem. I cannot recall the OBD code for the Saab but it was directly related to a failed thermostat.
 
Thanks for all your opinions. It was the thermostat. Car sits at about 90 degrees and loads of heat. Cheers G
 

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