Probably not a relay but the blower switch itself. The later model Trackers (yours) have a blower switch that sometimes comes apart, but if it has all components intact, can be fixed with pull ties. Do a search for blower switch fix on this forum. Good luckMy dash fan sometimes will not come on when turning th lever. Then the next time I start the car it may come on. It's about 50/50 odds. Is there a relay somewhere that needs to be replaced on these older models?
Thanks for any ideas!