• Jonathan, Thanks for your help in the past. I have a 1989 300E which has a problem with the climate control system. More often than not when I start the car ( warm or cold ) with the setting on auto and the EC button pushed in, the climate control system will not start on its own. If I push in the Defrost or AC ( solid white up/down arrows) the system will start. I can then push in the EC button and it will keep running fine. Does this sound like a control unit problem or tempurature sensor ? Something completely different? Thanks in advance for your help. Steve

• Most likely the problem is in the pushbutton itself.  Most temp. sensor
  problems make a control problem like all heat or no heat etc...   I know
  that the pushbutton is fairly expensive but a good rebuilt is available at a
  far lower price. I would recommend a rebuilt. There are only three  or four
  temp. sensors on the interior. Evaporator temp, heater case and ambient
  interior temp sensor up by your mirror.  A lot of older cars get this problem
  and most people live with it. They just press defrost and away they go. Make
  sure your problem isn't with the blower. Sometime the blower won't come on
  until it is given a boost by the defrost or the slightly higher a/c fan
  setting. Let me know what happens. JON
  
• 4/26/00

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