I need heater help

[70ChevyLongbed]

My heater blows heat into the cab... all the time. I have messed with the controls, which are broken off and behind the dash, and nothing stops the hot air altogether... it just blows less. Is there a way to disconnect/block off/stop the heater? The hoses in the engine compartment are new, but I haven't done anything with the heater or the controls. I don't have A/C and I won't need heat for 5 months or more, but with summer pushing temps into the 90's... I'm baking in there. Any help would be appreciated.

Oh yeah... I don't think this makes a difference, but here's a little more background...

The PO told me there was a problem with the heater controls so he wired in a toggle switch to turn the fan on and off. This past winter I realized that there was just as much heat coming from the dash area with or without the fan on. I disconnected the switch because it was wired directly to the battery and I was sure I would leave it on and drain the battery.