1991 Oldsmobile Cutlass

Hi, If you live in an extremely cold region, does the engine reach normal operating temp? Do you use a block heater? Do the heater hoses get hot, feel of them. Maybe the heater core needs to be flushed? If all that checks out, I'd have to look under the dash, maybe a directional door isn't opening or closing like it should. Maybe the hvac control is stuck on ac?