2005 Volvo S40 heat on passenger side staying hot.

You could have an issue with the passenger temp damper motor or the blend door is jamming up. The first thing you may want to have done first is to see if they can recalibrate the damper motors. Usually you need to do it aout 2 to 3 times to force it to take the calibration. If that does not work, they need to inspect the motor to see if it is bad? If the blend door is what is faulty, then the whole dash needs to come out to replace the climate control box.