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1979 Mark Fans Speed Questions

Bill -

The fan speed control works on all speeds except when you select heat then the fan does not come on at all also air is only Luke warm on economic vent or hi love. Also mode selector is very stiff to Operate. Thank yo,u have purchased from you in the past - you guys are great! I do have the Factory Shop Manuals.



Hi Michael -

The inoperative blower in the " HEAT " mode sounds very likely to be the very popular failure of the EVR relay ("Electro Vacuum Relay").

The EVR operation is explained on page 36-74-2 of your FoMoCo factory manual. The wiring diagram is on page 36-74-5 and the location drawing is on page 36-74-9. We can usually rebuild these if they prove faulty or replace with a good used one. Have this item diagnosed and let us know what you may need.