W204 fan at full speed and no AC

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New Member
Jul 6, 2023
W204 C-class
Hi lads,

I have an issue with a 2008 C-class (w204).

The radiator fan start spinning at full blast when the car gets started, even with cold coolant. Also the AC isn't working.
The fan and fan-regulator have been replaced with no succes.

Unfortunatelly there is no dealer close to me so reading the computer would be difficult. The car is also not insured, taxed or mot'd so driving somewhere would not be possible.

After reading a lot of forum posts I assumed it would be the AC pressure switch (3pin), when figuring out how to jump it for testing.
After disconnecting the connector, I found out both the power supply and signal wire have a constant 5V on them. Is this logical or does this point to a different issue?

Thanks in advance and if I need to provide more information or pics I'm happy to do so.

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