Recently replaced compressor and dryer, now blower is barely putting out any air, Blower blows when truck is cranked but does not work by just turning the key on. A couple of times it has not come on with the truck running..not sure if this is a switch, resistor or maybe the blower motor.. Thanks in advance.

 

Moving to the correct section.

 

Bad blower resistor, usually fan only works on high. Check for correct pwr at the blower motor. Could be motor going bad, ie high resistence.