Strange Clicking Sound in the Cooling/Heating System - Mercedes-Benz Forum

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post #1 of 2 (permalink) Old 07-20-2014, 04:44 PM Thread Starter
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Strange Clicking Sound in the Cooling/Heating System

Sort of hard to explain this problem, but here goes. We have a 2003 C240 AWD. When the car is started, for the first 15-20 seconds there is a series of clicking sounds - always 5-7 instances, then they stops. The sound sounds similar to the auto locks on the doors locking. But it comes from the a/c vents in the dash. The a/c fan also seems to stop blowing cold air as each "sound" occurs then rises quickly back up to normal levels before falling at the next "click". It only happens at start, then everything runs normally for the duration of the trip. About two months ago we did have to replace the condenser in order to get cold air blowing. Seems unrelated to that, but maybe. Any ideas?
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post #2 of 2 (permalink) Old 07-21-2014, 12:03 AM
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This is normally a broken flap in the heater box, there is a re set that you could try


To reset heater flaps and actuators

Switch on ignition.

Press recirculated air and defrost buttons on control panel together for longer than 5 seconds.

The LED's in the defrost and recirculated air buttons flash alternately.

Wait until the LED's stop flashing (approx 30 sec) system set to defrost LED on.

Switch off ignition.

After 40 sec re start engine.


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