Your blower motor is likely wearing out, increasing resistance, and thus increasing heat at the connectors. I would not continue using it due to risk of electrical fire. You should replace the blower motor. You need to inspect the power terminal connecting to the blower motor itself, and then you need to inspect the connectors that connect to the heater/AC control panel on the dash. Prepare to replace terminals, wiring, and connectors.
On mine, the wire and connector at the blower motor were melted. Also, pretty much all wires at connector C2 IIRC at the contro module were melted. All replaced all the wires, terminals, and connectors for the affected circuits. Was a bit difficult to find some terminals, as I believe connector C1 IIRC uses PC bow terminals.