Heater blower

Connected the vacuum cleaner and the flapper valves that divert air to the defrost, etc, moved, but the blower does not run in either heat or defrost. Seems strange to me that the blower would run with the A/C button pressed but not in heat or defrost. I'm thinkin that the new switch I installed that cost me $120 is defective. The wiring diagram is straight forward-- 12v to the switch with no different external contacts for A/C or heat, and no provisions for an engine temperature input that might delay the blower in heat and defrost.