Mike, there were three types if heaters for the ADs... "Re-circulating", "Fresh Air" and "Deluxe". The re-circulating did just that, re-circulated the air, the fresh air pulled fresh air into the heater, the deluxe had an option to pull fresh air or just recirculate. The "Deluxe" was first introduced in 1953.
The temp control was used on the "Fresh Air" and "Deluxe".
You probaly have the "Fresh Air" heater.
