Where would you start?

[69 Okie Truck]

Of all the old C-10's I've ever owned, some had A/C that may or may not have worked, but all had functioning heaters.

I went to try mine out the other day while I was home and found it inoperable.
Since I'm a long haul trucker, I reckon I'll get the catalog and start ordering parts to get her workin' when I'm back home in a few weeks. I'll need to get her goin' in one shot as I'm never home long before headin' back out on the road.

I thought I'd just replace a laundry list and then it'll HAVE to work....right?

My A/C blows cold, and I just got the truck in the spring so I didn't bother with heater thoughts until I needed it.

So....my heater fan blows, that much I know. Any ideas as to what parts y'all might order to ensure you got it goin'? It ain't so much cost as it is time in this case.....
Thanks in advance....