Find where the heater hoses actually pass into the car. They are usually found going into the car behind the engine at the firewall. There should be two black rubber hoses, about 5/8" diameter. With the engine running at operating temperature and the heater on, both hoses should feel pretty hot. If one hose is hot and the other feels cold or lukewarm, the heater core is most likely plugged.
this will tell you if heater core is working right. then if good it has to be in HVAC controls. the temp blend door is first suspect. by locating and watching if it operates while dialing heat will tell you if controls or actuator itself is at fault.see pic.

Answered by fixitmr
24 questions asked

Had the Climate controls changed and checked the heater door blend actuator which was fine but the heat still only come out of one vent and only when its on the control that pulls the air in from the outside. Also checked the fuses which were fine. What could be wrong with my car?

Response from jndixson01
2 questions asked

does it have separate right and left controls?

Answered by fixitmr
24 questions asked