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lillywilson1

Mercedes A Klasse Diesel Temperature Sensor Issue

My 2005 Mercedes A Klasse diesel shows a defective temperature sensor for the heat exchanger. The error is stored, an error message appears, and the AC won't engage. I suspect the AC control unit. Has anyone seen this, maybe with a coolant leak affecting sensor calibration?

4 comment(s)

philippweber6

I had similar AC issues and a dashboard warning light in my A Klasse. It was an engine cooling system problem. I found a small coolant leak near the heat exchanger. Have you checked for leaks or plausible sensor values and system pressure?

lillywilson1 (Author)

Can you describe the coolant leak symptoms you saw? Were there other issues like engine temperature changes or unusual cooling system noises?

philippweber6

The engine temperature rose slightly, especially when idling, but no unusual noises. Given the symptoms and error codes, a technician's diagnostic check is best. The AC control unit might be the problem as you thought. I had to take mine to a workshop because I lacked the tools.

lillywilson1 (Author)

I appreciate the detailed response. I'll consult a qualified workshop for a comprehensive diagnostic assessment to find the fault and get it repaired. Thanks again.

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