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You posted under 8145-20
8145-20 is time initiated, temperature or pressure terminated.Defrost timer training pdf
The 8145-20 timer:
Power leads connect to terminals 1 and N.
For 120Volt circuit: L is black hot wire to terminal 1, N is white neutral wire to terminal N
For 240Volt circuit: L1 and L2 are the hot leads from 240V breaker
'NO' means normally open, so terminal 3 turns ON only when timer turns on (that is 'time initiated')
So the hot gas valve for defrosting is connected to terminal 3 and turns ON when timer turns ON.
The other wire from hot gas valve connects to terminal N where it completes the circuit
'NC' means normally closed, so terminal 4 is ON at all times EXCEPT when timer turns ON.
That means fan is ON all the time, except when time initiated sequence begins, and then fan turns OFF while hot gas valve is defrosting unit.
The other wire from fan connects to terminal N where it completes the circuit
The cycle limit switch is connected to terminal X.
This is the switch that terminates the defrost sequence and turns timer OFF
Other wire from cycle limit switch connects to terminal N where it completes the circuit
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