Blower motor wont shut off

I have a 94 roadmaster that other than a short drive twice a year has basically sat since 2018. I have it up for sale and a prospective buyer and I took it for a test ride, near the beginning of the ride the blower fan started making noise. When we got back the blower would not stop running.
we shut the motor off. Nothing. I pulled what I thought was the fuse on the driver’s side of the dash to no avail. I finally had to disconnect the battery to get it to stop.
I have no idea how a motor could run with a power fuse pulled.
anyone have any opinion on what my problem is?

Probably a relay stuck closed.

https://www.rockauto.com/en/catalog/buick,1994,roadmaster,5.7l+v8,1022151,electrical-switch+&+relay,blower+motor+relay,3088

The motor control unit has shorted out. The unit can be repaired, but you must know how to do it. You can get a new one, or a used one to replace it.

Fred Kiehl wrote:

The motor control unit has shorted out. The unit can be repaired, but you must know how to do it. You can get a new one, or a used one to replace it.

Fred, are you taking this part or the motor relay listed by the other poster?

https://www.rockauto.com/en/moreinfo.php?pk=3902196&cc=1022151&pt=6557&jsn=10951

The part shown in the picture is the correct part. There is no relay.

Fred Kiehl wrote:

The part shown in the picture is the correct part. There is no relay.

Thanks!