No heat inside car

My wife's '93 olds cutlass ciera doesn't get hot inside the car; it barely gets warm. I have previously replaced the radiator, heater core and thermostat. In the summer, it runs really cool. Unfortunately, it also runs super cool in the winter. It doesn't have a heater control valve. The only thing I can think of is maybe the thermostat I used. I bought this "gimicky" thermostat that has a bypass hole drilled in it. Also, I don't think the vent doors are stuck, because I can switch the controls and feel the air changing to different vents. Any ideas?

Edit: I have noticed air blowing outside through the vents by the hood where the wiper blades are (when the blower fan is on), but I don't know if that's normal or not.

My wife's '93 olds cutlass ciera doesn't get hot inside the car; it barely gets warm. I have previously replaced the radiator, heater core and thermostat. In the summer, it runs really cool. Unfortunately, it also runs super cool in the winter. It doesn't have a heater control valve. The only thing I can think of is maybe the thermostat I used. I bought this "gimicky" thermostat that has a bypass hole drilled in it. Also, I don't think the vent doors are stuck, because I can switch the controls and feel the air changing to different vents. Any ideas?

Edit: I have noticed air blowing outside through the vents by the hood where the wiper blades are (when the blower fan is on), but I don't know if that's normal or not.

You may have an air bubble. When you replaced the thermostat, the hole needs to be pointed up. You can try parking on a hill, nose up. Remove the cap, and run it. See if it will burp.

I wanted to reply that I fixed the problem. I had bought a "no fail" thermostat a while back, in which if the car overheats, then the thermostat will permanently remain open - even after the car cools down. I don't ever remember the car getting hot, and makes me think the catch in the thermostat is designed for too low of a temperature. Anyway, the thermostat was the problem, and I replaced it with a "regular" thermostat. I'm never buying those gimicky "no fail" thermostats again!