E7 error code - how to swap the fan blower power unit

I have been getting the E7 error code and my AC/heat is shutting down on my 348. resetting the battery clears the error, but it comes back intermittantly. I bought a new power unit for $200 (even though my issue might just be a loose connection somewhere, I wanted the spare part). I took the inner trunk liner out to expose the blower unit and found the power unit part on the right underside of the blower unit.

so - how the hell does one change this. does not really seem readily accessible to change. the www.my348.com guide does not mention anything more than change the power unit. I might be able to squeeze in there, but its damn tight and will have to work blind. any suggestions? is it more realistic to get all refrigerant out and disconnect some hoses?

I plan to refill my r12 as the system is low.

http://www.ricambiamerica.com/product_info.php?products_id=254041