Perplexed by '64 Thrift Air Push/Pull Knob

[ACK]

I took out, lubed up, and reinstalled the Thrift Air cable in my '64 C10 today and what a world of difference.

Now that I can pull the knob out all the way, I feel a greater amount of air coming through the vents, when pushed in, it's like closing a damper and the air flow greatly decreases. If I can adjust the heater's air flow with the fan's 3 speeds, then what's the purpose of pushing and pulling the knob, or am I missing something?

[sigshooter]

That closes it off completely, otherwise hot air will continue to flow thru the heater even with the fan off.
Posted via Mobile Device

[ACK]

Originally Posted by sigshooter

That closes it off completely, otherwise hot air will continue to flow thru the heater even with the fan off.
Posted via Mobile Device

Thanks for the explanation.

[sigshooter]

I had mine apart this summer, had the square tube off under the glove box.... The hot air just flowed right on in the cab. The cable closes a flap in the tube right by the firewall that keep this out, otherwise you will cook in the summer

[kieth]

The fan of course controls the air flow, the in and out pull of the thrift knob controled how much heat you got.....regulated the temp.....high medium low......