I'm having a problem with heating my car. I have a manual system in a 2010 Sonata. Sometimes it feels fine, felt good today. But it will change and start to feel cool at times. I saw another thread about poor heating and it mentioned an actuator. I ordered one on the Parts.com website and am being told the actuator is not applicable for my vehicle. Is there an actuator on a manual system? And one other odd thing. If I put the selector on defrost, the A/C light will come on. I punch it off. I'll move the selector and come back to defrost and the A/C light will come on again. Any help would be appreciated and thanks in advance.