I had the same issue when I bought my car years ago. The convenience fuse kept blowing and the switch got so hot the plug melted. I swapped in a chinese rockauto fan and its been fine for almost 50kBeen having issues with my blower motor not putting out as much as as it used to. At 340k miles I figured it was getting about time to replace, as I'd already put relays on the circuit a long time ago to keep the switch from getting hot. Old motor was pulling 10.68 amps on high. I took one out of a parts car with a lot fewer miles, and that one is pulling 9.71 amps on high. At first it seemed like a good improvement, but now I think this one is weak too. I can't help but feel like maybe there's something inhibiting airflow, but I already fixed the blend doors and there's not any more foam in there. Doesn't matter whether it's on hot/cold, fresh air/recirc, or vent/defrost. I might have to take a chance on the $50 chinese replacement to see if it's any better.
As part of my troubleshooting, I wanted to see if the airflow would change any with fresh air vs recirculating it. Many years ago I rigged up the fresh air flap with a pull cable because the rubber diaphram was bad. I guess it had been in one position long enough that the cable froze up, so I tried pushing down the flap from under the hood. The flap went down, but I think it broke off one of the mounting tabs. I took photos of a spare hvac box I had to examine the linkage a bit better.
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Unfortunately I don't think there will be any fixing the actuation of the fresh air flap until I need to change the heater core (hopefully never!), so for now I have a hard drive magnet holding the door closed. I rarely ever opened it anyway.
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