I have a 2000 Grand Prix GTP. When I turn the heat on, the passenger side is ice cold but the driverside is warm, not hot, just warm. Any suggestions?
Have the cooling system flushed and bled by a shop.
There is most likely an air pocket in the heater core.
Have you checked your coolant/antifreeze level? Do that immediately.
Have a look at the temp gauge. Does it warm up to the same place it always has? If not you might have a stuck open thermostat (which is far preferable to stuck closed).
If none of those apply then you probably just need a shop to evaluate. You may have a plugged up heater core and/or a problem with the air control doors in the interior ductwork.
“problem with the air control doors in the interior ductwork.”
My MIL’s '04 Impala had that problem. I had to replace the motor that opens the air door on the driver’s side. It was kind of hard to get out, but the part was only about $30, IIRC.