I don't know if this is a malfunction or just normal so i figured i'd ask. It'* an '87, non-automatic temp. It'* tough to explain but i'll manage. It'* COLD here, lately 0-32 F. At first i thought the car didn't have any heat, because after it warmed up and i put it on the "vent" setting with the temp all the way hot. All that came out was cold air. But then i found out when i put it in either defrost or heat mode it will blow super hot like it'* supposed to. Any ideas why i only get heat from those two settings? I know all the vacuum lines for the air selector are working because it will blow air correctly in all settings, just only heat on the floor or defrost. Thanks for the input.

No one?

Do not have one so not certain but *think* the air diverter valve (one position you get outside air through a/c coils, other position is through heater core) on a non-ATC car is vaccuum controlled by the dash switch. Sounds like the switch is confused.