How I can remove the plastic fan off from the axle of the heating blower motor?

The vehicle is a Mercedes-Benz 308D van from 1992. The blower motor is a Bosch part number 0 130 007 027 which is described here. I know that also all Mercedes 207D, 208D ,209D, 210D, 307D, 308D, 309D, 310D, 407D, 409D, 410D vans, Volkswagen LT 28, LT 55 vans and Peugeot 305 from years 1983-1984 use the same motor, so people having experience with these vehicles can also help me.

The motor is broken, and I got a new one, but now I need to take the plastic fan off the old one to use on the new motor. The plastic fan attached to the motor looks like this:

and a photo from the other side:

I tried holding the plastic fan with one hand pulling the motor as hard as I can without feeling that the plastic might brake and also tried hitting the axle of the motor from the other side with a hammer, but neither method made it move even a bit.

Trying to rotate the plastic fan in relation to the motor axle doesn't work because I can't get hold of the axle with any tool hard enough not to have it rotate when I rotate the plastic fan.

Any ideas?

How I can remove the plastic fan from the axle of the heating blower motor?

The vehicle is a Mercedes-Benz 308D van from 1992. The blower motor is a Bosch part number 0 130 007 027. I know that also all Mercedes 207D, 208D ,209D, 210D, 307D, 308D, 309D, 310D, 407D, 409D, 410D vans, Volkswagen LT 28, LT 55 vans and Peugeot 305 from years 1983-1984 use the same motor, so people having experience with these vehicles can also help me.

The motor is broken, and I got a new one, but now I need to take the plastic fan off the old one to use on the new motor. The plastic fan attached to the motor looks like this:

and a photo from the other side:

I tried holding the plastic fan with one hand pulling the motor as hard as I can without feeling that the plastic might brake and also tried hitting the axle of the motor from the other side with a hammer, but neither method made it move even a bit.

Trying to rotate the plastic fan in relation to the motor axle doesn't work because I can't get hold of the axle with any tool hard enough not to have it rotate when I rotate the plastic fan.