Heater blower CLK

[horatio]

Have an annoying problem with my CLK's heater blower - it randomly stops working and then starts again out of the blue.

I have tried:
- a used fan
- another control panel
- checking fuses

Unfortunately it persists. Any thoughts? I suspect no codes would pop on a scanner.

I guess the used fan could be faulty but otherwise I have no idea.

Thanks