C220 2006 heater problem

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C220 evo s coupe 2006
Hi just bought a 2006 c220 coupe
Problem is the heater is eather red hot or freezing cold doesn't seem to matter what I set the temp too it's eather hot or cold noting in the middle please help
 

Paul Goff

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2002 C220CDi CD Estate
Morning Stephen,

Forgive me if I am teaching Grandma to suck eggs here, but are you allowing enough time for the system to control after you change the set point?
I am a warm individual and every car I've had with auto heating, ventilation and/or aircon have had a strong tendency to over shoot the set point wildly before settling down:confused:

What actually happens if you set your temperature control to 19 ish degrees, the fan to mid point, Auto to off, aircon off and then set out for a drive from a cold start? On my C220CDi the temp seems (to me) to go well over 19 for quite a while before it starts to blend in cold and then begins to settle at 19. All of which is normal behavior on my car and all of it's predecessors.

All that said, you could try the set up procedure for the system;)

Ignition on
Press and hold the demist (NOT heated windows) and recirc buttons together.
After a while the set up starts, the system will go nuts, cycling though every air direction and the temp from full hot to full cold.
If all is well this will stop after a short time but if the control unit senses anything amiss it will just carry on until you turn off the ignition.

What should have happened is that every control element, flaps, valves etc will have been fully exercised through their whole range of movement. Give it a go, it's quite amusing:geek:
 
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Morning Stephen,

Forgive me if I am teaching Grandma to suck eggs here, but are you allowing enough time for the system to control after you change the set point?
I am a warm individual and every car I've had with auto heating, ventilation and/or aircon have had a strong tendency to over shoot the set point wildly before settling down:confused:

What actually happens if you set your temperature control to 19 ish degrees, the fan to mid point, Auto to off, aircon off and then set out for a drive from a cold start? On my C220CDi the temp seems (to me) to go well over 19 for quite a while before it starts to blend in cold and then begins to settle at 19. All of which is normal behavior on my car and all of it's predecessors.

All that said, you could try the set up procedure for the system;)

Ignition on
Press and hold the demist (NOT heated windows) and recirc buttons together.
After a while the set up starts, the system will go nuts, cycling though every air direction and the temp from full hot to full cold.
If all is well this will stop after a short time but if the control unit senses anything amiss it will just carry on until you turn off the ignition.

What should have happened is that every control element, flaps, valves etc will have been fully exercised through their whole range of movement. Give it a go, it's quite amusing:geek:
 
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Hi there I went for a 2 hour drive yesterday and ended up having to open the windows it was that hot doesn't matter what the temp is set to it's red hot switch it to 16 and it's cold
 

Paul Goff

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Before you changed the setpoint to 16, what did you have it set to?
 
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18 red hot 16 freezing cold ??
 

Paul Goff

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My car is older than yours and has actual hand cranked twiddly knobs to adjust the temp:) Can I take it that yours has an electronic display/touch screen?

My knobs have a ratchet feel to them but at just below the 18 mark (16?) they noticeably "click" over to fully anti clockwise. This has to mean that I am telling the system "forget all this control nonsense, give me full cold, NOW". Selecting 16 (minimum?) on yours presumably does the same?

Yours does not seem to be controlling, which means that the controller isn't getting temp feed back from the sensor(s) and/or the controller isn't sending the relevant control outputs and/or some control devices are not working.

There are a number of motorized flaps and valves, all of which are known to get sticky, give the set up procedure a go, or several goes:D
 
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Hi no mine has 2 knobs it's a 2006 coupe does have a display
 
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Sorry it does not have a temp display
 

Paul Goff

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So, when you turn the knobs down to 16 do you notice a definite click as you do so?, The click is fairly subtle, you might not notice it while driving. Also, do the two sides behave in the same way, temp control wise?
 
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Yes there is a definite click
 

Paul Goff

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Your system sounds very similar to mine, go on, give the set up thing a go, you know you want to! :geek:
 
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Hi just tried the reset lights flashed for about 15 seconds then went off so I take it there are no probs there but heat is still the same I might try a new heater control unit
 

Paul Goff

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Probably best to get the car on a STAR machine next, that can narrow the problem right down.

Oh for the good old days of three hefty plastic levers directly operating air mixing/direction flaps and a rotary 4 position switch for the fan.
 


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