The fresh air blower on my 71 works very well while driving with the RPM's up, but sitting at idle.... the speed and quantity of air is barely dectectable. Shouldn't the fresh air blower speed work the same regardless of RPM?

Suggestions or advice is appreciated.

Thanks!!

Your blower is not coming on. The heater blower supplements flow of hot air from the engine cooling fan through the heat exchanger, heater and df.

The fresh air blower in the front trunk is for cool air ventilation.

The action you describe is typical of heater performance without a heater blower, i.e., the normal flow patterns from the engine fan. VW Beetles and early bus don't have blowers and their heat works precisely as you described.

The output of the fan housing has small metal flappers. Maybe yours are stuck open or missing. These are meant to prevent the blower from pushing air into the fan housing at low motor speeds.