16
Page
240 (T-H3J), 340 (T-H3S) and 540 (T-H3) models Service Manial
Ver. 1.00
CONFIDENTIAL
7. Wiring diagram check points for diagnosis
The table below applies to both the the Direct Vent Indoor models and Outdoor models.
Check-
point
Part and Description
Color of wires
Normal range
A
120V Power supply
White – Black
108 to 132 VAC
A1, A2
120V Power supply
Black - White
108 to 132 VAC
B
Igniter
Purple - Purple
108 to 132 VAC
B1
Heater
Yellow - Yellow
108 to 132 VAC
C
Gas valves
Light blue - blue at COM (MV)
93 to 120 VDC (during
operation) / 1.35 to 1.65 kΩ
Green - blue at COM (SV1)
93 to 120 VDC (during
operation) / 1.35 to 1.65 kΩ
Orange - blue at COM (SV2)
93 to 120 VDC (during
operation) / 1.35 to 1.65 kΩ
Red - blue at COM (SV3)
93 to 120 VDC (during
operation) / 2.07 to 2.53 kΩ
C1
Hi-limit switch
Blue - Blue
Less than 1 VDC
and
less than 1.0 Ω
C2
Overheat cutoff fuse
Blue - Blue
Less than 1 VDC
and
less than 1.0 Ω
D1, D2
Easy-link connectors
540 (T-H3) models only
Black - White
15 VDC
(during Easy-link operation)
E1
Outlet thermistor
Black - Black
See table on p. 18
E2
Inlet thermistor
Black - Black
E3
Heat exchanger thermistor
540 (T-H3) models only
Black - Black
See table on p. 19