If only the passenger side is not heating up, that would most probably be due to a fault with the air mix actuator.
Is vehicle equipped with manual or automatic HVAC?

Answered by KHLow2008 (expert)
39,924 answers provided

I don't know and the car is at my daughters. I'm just trying to figure out if I failed to protect her from an expensive repair.
I am somewhat relieved by your response. My e-mail is rberens1945@gmail.com. I won't see the car again til after 1 today (Sunday).
Bob Berens

Response from rcberens
1 question asked

Since you have just bought the vehicle, most probably you should have a warranty on it if is is from a dealer so you should let them know about it and get them to resolve it.

When the heater is working correctly except for certain vents, it is not a major problem. The air direction are controlled by vent movements and for the heater, there are air mix actuators moving them from heater to A/C positions. If the actuator fail to work, which are common faults for any makes or models, the heat would not be sufficient as the air is not passing through the heater core when it comes out of the vents.

The repair won't be too expensive nor difficult and might even be a simple job as reattaching a dislodged link or loose wire connector.

Answered by KHLow2008 (expert)
39,924 answers provided