My Mercedes Benz 1982 - 300SD has the following problem: Every time that I need to use the CCU push buttons it does not work. Sometimes after push the Defrost button on and off couple times I can get the fan and AC running but many times even doing it the fan and AC compressor does not work. When I get the fan and AC running using the Defrost button, I wait for almost three minutes running and then I switch to another button to keep it running. I checked all fuses and relays related with AC and CCU system and all are OK.
Not matter if it is winter or summer the symptom is the same and if it the system work at the first time it can also quit work at any time. I read many posts and threads about this issue and I got good tips from others but now I am wondering from where the problem is coming from and how to start to fix this problem since summer is started and a good AC is needed.
You help is extremely appreciated.
Thanks.
Nyko 46.

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Nyck - TX - USA