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Good morning,
Does anyone happen to have a wiring diagram for a 77 f100 I have been to fordification and 77 is skipped and the owner says he can’t find his 77 book. I tried working off of the 76 diagram but there are small differences and the 78 is nowhere close.
I have factory ac I have checked the switch with an ohm meter it functions as it should if I apply 12v to the fan switch connector all 4 speeds work. I have 12 v coming out of the orange and green and white wires on the function switch. Ac compressor is running and the condenser is cold and when I turn the fan on with a wire it blows cold. In the 76 wiring diagram it shows a relay and it says in the engine compartment in the middle of firewall. I have nothing there. On the 78 diagram there is no relay at all.
Good morning,
Does anyone happen to have a wiring diagram for a 77 f100 I have been to fordification and 77 is skipped and the owner says he can’t find his 77 book.
I tried working off of the 76 diagram but there are small differences and the 78 is nowhere close.
THREE different types of A/C in these trucks, factory and two types of dealer installed A/C
Most people don't know one type of A/C from another.
Factory installed integral A/C is combined with the heater. The A/C controls are in the same panel as the heater controls.
At the right rear of the engine compartment, is the HUGE factory A/C evaporator case.
The factory A/C blower motor and blower motor resistor are the same 1973/79.
Some 1973/75's use different parts than 1976/79. If the part fits a 1976, it'll be the same thru 1979.
Blower motor resistor shown as 19706 in pic. 19618 is the A/C evaporator temperature control thermostat. 19849 is the expansion valve.
THREE different types of A/C in these trucks, factory and two types of dealer installed A/C
Most people don't know one type of A/C from another.
Factory installed integral A/C is combined with the heater. The A/C controls are in the same panel as the heater controls.
At the right rear of the engine compartment, is the HUGE factory A/C evaporator case.
The factory A/C blower motor and blower motor resistor are the same 1973/79.
Some 1973/75's use different parts than 1976/79. If the part fits a 1976, it'll be the same thru 1979.
Blower motor resistor shown as 19706 in pic. 19618 is the A/C evaporator temperature control thermostat. 19849 is the expansion valve.
Mine is the factory air and the resistor is functioning properly, along with all the ac components. It is just the fan not working and no voltage to the fan speed switch.
here is a thread with a picture of the relay. I always thought the relay was a 1976 only thing...but if you '77 has it, you can follow the yellow w/red strip wire from the mode switch and it should lead to the relay...
here is a thread with a picture of the relay. I always thought the relay was a 1976 only thing...but if you '77 has it, you can follow the yellow w/red strip wire from the mode switch and it should lead to the relay...
It disappears into the harness I will try to track it down out cruising it now lol.
and the 78 is nowhere close. 
