When my fan went, it also took out the isolation mounts.
To replace them, I took the A/C mounting bolts out and lifted the back of the A/C unit just enough, about 6" to 8", to get my hand and a wrench under it to take the old bolts out and put the new mounts in. Not hard at all - except the A/C mounting bolts are about 8" long and having to work over my head, and I didn't have a socket to fit my drill motor!
Rick & Debbie; Brandy & Schnoodle Dexter & Fritz R.I.P. the Doxie "Kids"
2015 Jayco Pinnacle 36RSQS 5'er
2013 Chevy Silverado 3500HD LTZ, 6.6L Diesel Dually; B&W Goose Neck and Companion 5'er hitch