My German dealer (Panda-Solar) has rejected my request to the SPR00090 retrofit kit, since I have the units with the relatively new Serial Numbers.
The picture shows the voltage trace measured directly at the fan connector at low RPM.
The picture is the proof that:
The unit HQ2250EY7AN has the issue factory solved.
The unit HQ2250XCM4P has the 25Hz issue unsolved.
your Document regarding the retrofit kit says that only the units build before HQ2224 are affected, but this is not true.
Please provide the official statement that the unit HQ2250XCM4P entitled to have retrofit kit been installed. I need this statement for the communication with the dealer.
Regards,
Update 24.09.2023:
Please read my report (pdf attached)Further investigation of the 25Hz fan control issue on the HQ2250XCM4P unit.pdf