hate to be the bearer of bad news.......my '98 did the same thing. everybody told me the speed control resistor. i knew otherwise-that resistor allows the blower motor to blow at high speed only when it goes bad.
so squeezed myself under dash & inside wiper cowl(between hood & windshield) & my VOM told me voltage getting to blower motor & resistor was good. i asked here, got link to 'how to replace blower motor' and YIKES! book repair TIME IS 10+ HOURS!!!!! you practically remove & replace the entire dashboard of the truck!
so i wheeled & dealed with my mechanic who does what i can't/don't want to do. what i found is:remove everything including front passenger seat, entire dash including airbag & everything underneath the dash. THEN you remove the climate control box.....and all the little connections, lines, etc. THEN you eventually get to the blower motor. which needless to say, BURNED OUT. about 30 bucks! also, while in there, remove coolant from AC system & replace evaporator & ANYTHING ELSE that may need replacement before you dispose of your durango 'cause you DON'T wanna go through this again!
power washed the box which had some deformity in the blower housing and lots of mulch(read
ld leaves) PLUS the remains of at least 1 rodent-just his bones. was going to get a new box, but none in junkyards here, dealer was a 2 week wait AND price was exhorbitant (don't remember, but it was HIGH.) so put in NEW blower motor (no rebuilds here), replaced evap & a few minor items he recommended, replaced everything, dired it up & good to go!!! on the negative side, it sounds like a leaf caught in the blower, but we did everything we could & it's because of the deformities to the box/housing. it spins free & true, isn't touching anything, there's no drag/excessive current draw due to drag, so i said a few hail maries & let it go. charged up the AC & things work fine(knocking on wood/head).
actually required 3 days, 1 to disassemble, 1 to diagnose, replace & gather parts & 1 to reassemble. total hit to my wallet? $1200. had asked dodge before i got his estimate. dodge's estimate? DOUBLE!!! yup, $2500 for all recommended replacement parts.
yes, it blew hot air just fine at 60mph, even with temp in teens. that was november. no way was i gonna not fix it. it was 5 degrees last nite, 22 today, below zero tonite ando only in the teens tomorrow. probably could have gotten away with not doing it-IF i drove at 60mph all the time. but that wasn't happening.