Dismantle the driver's side first so you have a clear idea of how and what needs to be done on the passenger side regarding the fan blade and clip.
Use a hole saw on the passenger side big enough to work through.
Press a thin bladed screw driver against the motor shaft when you release the passenger side clip so it slides down the screwdriver and out of the heater matrix.
There's a clip holding the outer shell like the ones you CAN see on the driver's side that you can't see--way up on top--use your hand to feel it. If the outer shell doesn't come loose you didn't get the top clip.
I've done this job both ways--you will save time by not having to completely disassemble the passenger side. You should remove the glove box for better access and vision. -- Dave