My 02 Silverado doesn't have any fan on speeds 1,2.. All the other speeds are fine. Could this be the HVAC unit itself??

 

no its the risistor that is covered by the black cover underneath the dash, go to the parts store and get the a/c resistor it's like $30 should take about 10 min to install.

there are like 3-4 7mm bolts holding the cover on i believe and one is towards the middle of the truck and it's a bitch to get to, and then once you get that off another two bolt and it's the plug that has 5 or so wires going to it.

 

Oh, I thought the resister was only for high speed??

 

no it's for all speeds i believe, my truck did that for a while, 1 and 2 didnt work only 3 4 and 5 replaced that and wamboozle it worked like new again.

 

check your passenger air compartment filter if that clogs up it will cause the resistor to burn out faster. I think air flow over the resistor cools it.