When you test for power make sure
The keyed ignition switch is ON
The selector switch needs to be in any position EXCEPT OFF
"The front blower feed comes from the orange/black wire which comes from the blower motor. The power is fed from a fusible link and passes through the blower relay when the mode switch is turned to any position besides OFF. Once it passes through the relay it goes through the blower motor to the blower switch. You would want to first check the power from and to the blower motor to see if it is present to that point, with the switch in vent mode and blower on HIGH(test mode incase the resistor is bad which might otherwise hamper diagnosis), and check for power on the orange/black wire at the blower motor (with blower plugged in) as well as on the orange/red wire at the blower motor. If power IS present on the orange/red wire but not the orange/black then the blower motor has an open circuit and is bad, if no power on the orange/red wire ,then either the relay has failed, or the mode switch is not sending power to the relay to turn it on. by jumping the 2 main terminals on the relay you can test the blower motor and its associated wiring as well as the fusible link, if the blower operates then that part of the circuit is ok and the fault lies with the relay or the mode switch. another easy test is to swap out the relay with a known good unit , as relays are common to fail when older. "
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No Power to Heater Blower | FordForumsOnline.com