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79 300SD heater problem

2K views 5 replies 4 participants last post by  peoples28 
#1 ·
So the other day was the first day of the fall so far that necessitated using the heater, and upon hitting all the buttons only defrost works, and that only blows out lukecold air.

Does this mean its time for new heater core or ?

Any advice would be greatly appreciated :)
 
#5 ·
Classic symptom of a failed ACC Amplifier, although that may not be your only problem. Replace the Amplifier (behind the glove box) and see what you have.
 
#6 ·
that could be ur servo

If there is nothing wrong with the heat or ac systems it is probably the servo.
Especially if you never replaced it and if it isnt the new digital upgrade.
You can find a new servo at performance mercedes.com.
 
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