Heater blower motor problem

Hello everyone. I've got a problem with my heater blower motor - it starts to work when it wants. Some times a minute or two after the engine starts, some times it doesn't work at all.When it happens the AC doesn't work as well. I've checked fuses 1 & 12 in the internal fuse box, but they are ok. So, any ideas? what could it be? Thanks in advance.

resistor 

do a "search" for resister,where you will find many answers to your problem. paul