Unit: "Old" Sears Furnace Age: Unknown; Model#: 867.763271; A/C: Kenmore condenser/cooling coil are newer add-ons probably mid-90's; Blower Fan: Emerson 1/3 hp direct drive, looks-like updated model.

Problem: Recently, the blower fan on our furnace stopped running and yet the condenser continued to run. While inspecting the blower fan, I found a manual circulation switch on the bottom of the Electrical Comfort Center inside the furnace and switched it on and the blower fan started. I suspect the double pole double throw Plug-In Relay, but not sure how-to test it to verify. Any other suggestions would be greatly appreciated. Thanks.