2004 Monte Carlo SS. Engine 3.8L K model. Checked fuses & good. Replaced A/C heater control unit. Question: My car has dual climate control and the drivers side is not producing any heat while the passenger side does.
Answer: I'm going to have to assume that the driver's side still blows cold air conditioning, rather than none at all. An easy first step is to try to calibrate the actuators for the HVAC system. You can remove the fuse for the HVAC system for approximately 1 minute, then reinstall, then on the next key cycle the control head will recalibrate and re-home the actuators. Don't touch any controls for 2 minutes. If that doesn't work, you probably have a faulty actuator on the door that controls the cold/hot air to the driver's side. Not a simple fix, but not extremely difficult if you are mechanically inclined.
To replace the temp door actuator for the driver's side you will need to remove the lower dash trim and kick panels on the LH side of the dash. The actuator itself is on the left side of the heater case held in with three small screws. You may want to have a local dealer show you a picture so you replace the correct one. After removal of the old one, you will have to line up the cam on the actuator with the lever on the door. This may take a couple times to get it right. Once the new one is installed, recalibrate again and you should be good.