Originally Posted By a_d_a_m
I would've guessed it's the blower motor resistor, but when those fail, they usually default to working on the highest speed setting...

Yes, I believe they do that with a relay or something. Fuse is a good place to start, and stupid cheap to boot
Current Panther:
1999 Crown Victoria LX - 69,420 miles (nice) as of 1/27/21, Toreador red, 18x8 Anthracite Torq Thrust M's, AEM Dryflow panel filter, custom 2.25" dual exhaust with H-pipe, Magnaflow XL mufflers, Jones 22" long 4" slash cut tips, Kenwood KMM-BT225U head unit, PPI A600/4 4-channel amplifier, PPI i650.1 monoblock amplifier, Pioneer 6x8 2-way speakers, two 12" JBL subs in sealed enclosures, 2/2019 to present

Past Rides:
2003 Buick Regal GS Joseph Abboud edition - as close to a Grand National as I'll probably get, traded in 2/2019
1996 Lincoln Town Car Signature - 1st car ever bought, dubbed "The Emancipator" by friends, rear ended and totalled in 5/2016
2002 Buick Rendezvous CXL - passed to me by the folks, handed down to younger brother in 2/2015