1990 Acura Integra RS 5-Speed Manual

Hi,

I'm a newbee at this. The fan switch has four speeds and the first and second speeds don't work but the fourth and fifth do. My AC works well, everytime I turn on my AC I have to turn it up to speeds 3 or 4 but 1 and 2 don't work. Is it the blower motor? Please help.

Thanks Very Much,
Chai