My 99 DSDP has two fuses ( inline ) behind the return air grill , and if one or both are blown , the furnace circuit , doesn't report back to the front roof A/C unit and show up on the t'stat display .
Grill is Velcroed to the cabinet face . Pictures taken with grill removed.
NOTE: Actual location of the two fuses varies by the installer working on the day your coach was built , other owners have found them , behind the outside furnace access panel .
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.