1993 GMC Sonoma Owner's Manual - Page 133

Heating System KO505 If yourvehicledoes not haveairconditioning, systemwill look like. this iswhatyour heating Fan Lever The lever at the top of the systemhasfour positions. To increasetheair flow,move the levertoward HI. To decrease the airflow,moveittoward OFF. Temperature Lever The lever on theleft of the systemletsyouselect the temperature of the air flowing into yourvehicle.Movethelever up forwarmerair.Move the lever downforcoolerair. Function Lever Theleveron the right of the systemcan be moved to threedifferentheating functions. DEFROST This setting operatesthedefroster.Most of the aircomesout nearthewindshield,withsomegoing to the floorvents and sidewindow defrostvents.Use this when you get fog or ice on the windshield. HTR (Heater):Most of the aircomesoutnearthefloor.Therestcomesout from the defrosterventsunderthewindshield and at the front sidewindows. This is best for cold weather. VENT Theaircomesout front side windows. at the vents on yourinstrument panel and atyour 3-5