jorb,
Yes, the 53-55 air flow heater's open-door to the outside and the heater-fan (with the heat turned-off) allows forced ventilation with outside unheated "summer" air.
That's right, I forgot about that, the air flow heater's have a temperature control rod/valve to
completely shut-off engine heated anti-freeze coolant from circulating through the heater core.
Did all air flow heaters come with a temperature control rod/valve?
