Dual cloimeate control blows hot on one side and

Does the vehicle have dual zone climate control, where the driver side and passenger side have different control? Sounds like a blend door issue on the driver side. Why did you replace the passenger side, was it blowing hot too when AC was on?

Check the actuator motor on the heater it directs the air into the vents. There is probably two of them be sure to check both. The motor makes the vents move and again directs the air where you want. Hope this helps.

Blend doors control flow between hot and cold airflow . In a dual system both sides have their own separate blend doors . Possible bad switch, connection or wiring that need checking out .

Sounds like a blend door actuator failure,Might as well replace both sides

My 02 Century has dual temp controls . One for driver for passenger. Make sure you don't have the dual climate enabled and just set for heat on your side and AC on the passengers

if it has dual zone climate setting it could be stuck in the cool setting. if it is not blowing any air it could be the duct came loose and it is blowing the air inside the dashboard. it will require you to pull the dash apart to inspect what the exact cause is. it could be anything from a bad temp setting switch in the climate control panel to a bad vac line that that switches the air from hot to cold. any other info you could give me may help such as if it is full electronic climate or manual knobs, dual zone, is it blowing any air or just no hot air.

Its more then likely the temp door broken or temp door motor broken/stuck. There is 2-3 of these motors under the dash on the side of the evap/heater core box. Some require extensive labor to replace, good luck

seems like you dual climate switch is malfunctioning, try replacing the climate control cluster and im pretty sure that'll do it

Touareg passenger side only blowing cold air 2003 3.2 v6 dual climate control

I would assume with multiple people having the same problems, there should be a service bulletin on this issue. may want to call dealer with vin # to verify. sounds like a heater control issue under the dash. something i would leave to the experts for repair