Ac completly rebuilt worked fine now, works once in awhile then nothing could it be a faulty relay or fuse

I looked at 05 avalanche 1500--automatic hvac. The blower fuse is hot all the time. The fuse has an input leg and output leg, even if the fuse is blown, the input leg would still have voltage. If no voltage, you could use jumper wire connected to voltage on the output side of fuse cavity to see if blower would work. If you use jumper, use an inline fuse.
Yes, it could be something wrong with fuse box or wiring circuit?

fan motor probably faulty use a meter to test freon level would be compressor not fan problem

There is a relay that powers the blower motor circuit . Left I/P fuse box , do you know where that is ? The relay is IGN 3 relay .
Fuse Block- I/P - Left
LF of the passenger compartment, behind the kick panel
IGN 3 RELAY
--
IGN3, HVAC CNTRL MODULE
IGN 3
10A
HVAC CNTRL MODULE, TC SW., HTD SEAT SW.
Does your car have Manual or automatic climate control ?

The blower motor itself or the blower motor resistordo the resistor its faulty

read the owner manual to see how the auto works. try the defrost mode whcih is a fail safe mode and should always come on unless a major system issue.

CHECK AC COMPRESSOR FUSE OR RELAY.IF BOTH FUSE/RELAY GOOD.PROBABLY YOUR REFRIGERANT TOO LOW.FAULTY AC REFRIGERANT PRESSURE SWITCH OR OPEN AC COMPRESSOR CLUTCH COIL OR PROBLEMS WITH THE PCM.

its not a fuse i had the same problem on my 03 x5 it an ac resistor thats at fault it controls your fan once it goes your fan wont come on or comes on intermitently once again the faulty part is a blower motor resistor should be 100 bucs at dealer or if you shop around i got mine for 75 from local parts store (carquest)

Check the relays

Change the 15amp fuse in the kicker fuse panel labeled cig. My stopped working for the same reason.

Ford uses a relay system for the compressor clutch, have someone turn the a/c on while u listen for the relay to click. If you can hear it click check the compressor clutch wire (2 wire plug) to make sure it actually has power. the 6 and 10 series compressors that Ford uses are known to just fail all at once.