1969 C-10 Heater question

[mjm0103]

Wow this board is awesome!

My son just bought a 1969 C10 w/ factory A/C for his 1st car. It runs great, but needs some tinkering with here and there. I've learned a tremendous amount already from reading this board. It's given me the courage to dive into the car deeper than I would normally feel comfortable with.

Our first task is to try to get heat into the truck. The blower blows great, but no heat. (A/C doesn't blow cold air either...but that's a task for another time) Also, when we move the "temperature" lever all the way to the right for heat, the lever would not stay in the far right position. It would move back about 1/4 to 1/2 the way. We spent a few hours cleaning out 30+ years of leaves, debris etc. from the vents plus putting in new vent and defrost hoses (the old ones were brittle and cracked) under the dashboard. That ended up giving us "luke warm" air after running the truck for :30 minutes. Also I'm not sure why, but after cleaning out that debris, the "temperature" lever now stays all the way to the right like it's supposed to when we push it over. I would like to get in behind the heater core to clean out any debris there, but I am not sure the best approach. I got under the dashboard and opened up the diverter box to where I could see the heater core inside. I'm not sure if the best way to get "behind" (the other side) the heater core is to completely remove the housing underneath the glovebox thats bolted to the firewall or if the only way to clean out leaves and debris would be from under the hood.

When I was under the dashboard I saw 2, maybe 3 bolts holding the diverter housing to the firewall. Those came off easy enough. But there are several round headed bolts with what look like metal slip on clips as well that appear to be holding the diverter box to the firewall. I tried slipping off one of the clips but it didn't seem to want to slip off. Again, it appears that these hold the housing to the firewall, but I'm not real sure. Does anyone know if removing this housing would give me access behind the heater core? If so, how do I get the danged thing unbolted from the firewall?

Since the truck has A/C the heater core box under the hood has more plumbing to it than a non-A/C. Most of the threads I've read here discuss non-A/C heater core removal, so I'm reluctant to start unbolting under the hood until I'm clear on the steps involved.

At this point all I want to do is make sure there's no blockage in the heater core. The vents were literally packed solid with debris so I'm suspecting to find similar pileups by the heater core.

If I can do that and still don't get heat, my next steps will be to replace the Thermostat since it's simple enough to do. (I did notice after running the truck for an hour that the temperature gauge barely rose past the "cold" mark...it definitely did not rise to half way between cold and hot as I would have expected) The radiator fluid level is fine. Also after running the truck for an hour, I felt all the plumbing going in and out of the heater core under the hood. They all felt about the same temperature. One wasn't hotter/colder than any of the others. Any other thoughts?

Thanks again for a great board.

Ken