I had the same issue on an AC blower which is slightly larger than the heater assy and there is no good place for a gear puller or anything prying behind the wheel without risking damage.
For the AC wheel I was able to add something for a gear puller to grab by using an
inexpensive shaft collar with an ID that was for a shaft just slightly larger than the hub. Drilled and threaded two holes in the collar for a pair of set screws.
Clamped the collar on the hub with the clamp screw and some shim stock then used the added setscrews for the real grab with one of the added setscrews going into the original setscrew hole and the other solidly against the hub. Then used a small gear puller to pull the wheel off.
As I recall the shaft was recessed in the hub a little bit so I had to use a short bolt to drop down in the hub and touch the end of the shaft so the puller had something to push against.
This Post was from: https://packardinfo.com/xoops/html/modules/newbb/viewtopic.php?post_id=223786