Correct ECM Fan Controll Wiring

Correct the Control Wiring Problem or Replace the Thermostat.

Check the Mfg. wiring schematic.  In general, ECM condenser modules receive 24 volt signal from the Y1 and Y2 terminals. Verify control voltage between Y1/Y2 and the common line of the transformer.

When checking control voltage, always use the common side of the circuit and not ground. Contactor control voltage generally originates from the AH/Furnace transformer and then to the thermostat (often on the R-red control wire).  On a call for cooling the thermostat closes a switch transferring voltage to the cooling control wire (often on the (Y)-Yellow wire).  The current is then sent to the outside condenser, and may pass through one or more pressure, temperature or other safety devices before finally reaching the contactor.

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2 ECM Low Voltage