2005 blower sometimes works sometimes doesnt

Can someone please guide me in the right direction. I have a 2005 caravan that has blower problems. sometimes when you turn on the heat or ac, it blows normal on all speeds, but other times it doesnt blow at all. Its like an all or nothing kind of thing. It seems to be happening more frequently lately. when it does work it works on all speeds. if anyone knows what this is, please let me know what it is and the location of the part. Thanks.

First thing to try is swap the front blower relay with another identical nearby relay on the Intelligent Power Module (IPM - fuse/relay panel) next to the battery.

My Dakota and Caravan have both needed the blower motor resistor replaced. Cheap part that stops the blower from working. It can be intermitent at first. Eventually it will stop. Easy and cheap fix.