Lennox MS8 SERIES Installation And Service Procedures page 87

15. COMPONENT: INDOOR TRANSFORMER
DESCRIPTION:
Indoor unit contains a transformer that will convert the 115
power to 12VAC or on some units there are two output
voltages. The transformer in the pictured shows a
transformer that will output 12VAC (yellow wires) and
8.5VAC (white wires). Output voltages will vary with input
power into transformer.
16. COMPONENT: INDOOR / OUTDOOR
COMMUNICATION LINE
DESCRIPTION:
These units can use the same wire insulation and gauge as
the main power wire into the system. The wire is routed from
the outdoor unit to the indoor unit.
TROUBLESHOOTING:
Use a true RMS meter to read between terminals 2 and
neutral. The communication signal can vary:
S
9 and 12kBtu indoor Units - 0 to 70VAC.
S
18 and 24kBtu indoor units - 0 to 56VAC
S
30Kbtu indoor unit - 0 to 15VAC
TRANSFORMER
Page 87
TRANSFORMER INSTALLED
IN INDOOR CONTROL
HOUSING
Corp. 1244-L9