There is, I think, a TSB on this condition that says the temp control door inside the dash air box warps over time and causes it. Common problem. The culprit is a design flaw in the temp controller, admitted by a GM engineer I spoke with. The sensor gets "confused" with the temperature in the car and decides the driver needs heat. The system diverts a flap that routes warm air and AC to the driver, while the passenger side gets only AC. If you can stand it, the system usually adjusts correctly after several minutes. There are several reset sequences floating around the net, such as pulling fuses, disconnecting the battery, leaving doors open, etc.. None of these worked for me. I have found that avoiding the "auto" setting by turning on the system by first hitting the outside air button, then the ac, then adjusting the fan brings the system up correctly, especially on a hot day (thank goodness). Make sure the driver temp is turned to 60
The heater coil is leaking. Water from the cooling system runs through the heater coil to heat the passenger compartment. Antifreeze is corrosive, some heater coils are thin.
The heater blower is located inside the passenger compartment just above the passenger side floorboard. If your seated in the passenger seat, look directly above your left foot.
If the heater still works the bulb is just burn out. I doubt you can change the light you will have to replace the switch.
it's on the outside on the passenger side.near the heater core hoses.
You will need to remove the water supply hoses from your 1998 Oldsmobile Intrigue heater core. Remove the heater core retaining bolts. Reverse the process to install your new heater core.
The heater blend doors have failed. It is likely that the drivers side has failed shut whilst the other side is stuck partly open.
In line on the heater hoses on the passenger side of the engine. Has a small vacuum line to it and both heater hoses go through it. The heater hoses are smaller than the radiator hoses and go through the firwall.
Wet foot in driver area means leaking heater coil. The heater coil unit is usually at the center of the front of the passenger compartment, behind the dash and very close to the floor. Heated radiator water passes through this unit and your vent system and fan are used to force air across this to heat the air in the passenger area.
Antifreeze will be leaking in the floorboard on the passenger side, there will be a smell of antifreeze through the vents.
heater core leaking
The heater core is located on the passenger side, not the drivers side. You do not have to remove the steering column or any parts around it.
Behind the firewall, near the center of the engine compartment.