520 Indoor / 520 Outdoor Service Manual
Ver. 1.00
13
CONFIDENTIAL
Check-
point
Part and Description
Color of wires
Normal range
E1
Mixing thermistor
Black - Black
See table on p. 14
E2
Output thermistor
Black - Black
E3
Inlet thermistor
Black - Black
F
Remote controller
*
11 to 25 VDC
G1
Fan motor
Red – Blue
Yellow – Blue
Orange - Blue
110 to 160 VDC
13 to 17 VDC
2 to 6.5 VDC
G2
Fan motor for exhaust
H1
Gas proportional valve
White - red
1 to 15 VDC
(during operation)
and
20 to 40
Ω
H2
Flow sensor
Red - Black
4 to 5.5 VDC
White(+) – Black(GND)
1 to 4 VDC
(1,200 pulse / min)
I
Air-fuel ratio rod
Yellow - AFR rod
(Between AFR rod and
the computer board)
More than 1
μ
A
(during operation)
Flame rod
Orange - Flame rod
(Between flame rod and
the computer board)
More than 1
μ
A
(during operation)
J
Water control valve
Blue – Brown
Orange – Brown
Red – Brown
13.0 to 16.0 VDC
ON: 12.5 to 16.0 VDC
OFF: 0 to 1 VDC
1 VDC Less ( 0° position)
K1
Exhaust thermistor
White - White
See table on p. 15
K2
Hi-limit switch for exhaust
White - White
Less than 1 VDC
and
less than 1.0
Ω
