Lennox Merit MPE36 Service Manual page 10

To test the transformer:
•Remove the low voltage connector (two red wires) from the control board as
shown. On the side of the connector two silver terminals will be visible.
•Set your Multimeter to test AC voltage. Touch the probes to the two silver
connectors on the transformer wires. Voltage should between 16 – 18 VAC
•When the transformer is reconnected to the board there should be two
"beeps" should be heard confirming "power up" of the control board.
Probes connected to
transform wire terminals
16-18 VAC