7 Circuit diagrams Thermo 90 S / Thermo 90 ST
706
Fig. 705 System circuit for Thermo 90 ST, 12 and 24 V, with standard clock
ϑϑ
Temperature coding (temperature at water outlet):
See table on page 302
Digital timer P2:
with positive at connection 10 = Continuous operation with immediate
heating
Connection 10 open = Variable heating duration can be
programmed = (10 min to 120 min);
= Default setting 120 min
Vehicle fuse
Vehicle fan switch
1
2
3
4
Cable cross-sections
< 7.5 m
7.5 - 15 m
0.75
mm
2
1.5 mm
2
2.5 mm
2
4.0 mm
2
1.5 mm
2
2.5 mm
2
4.0 mm
6.0 mm
1.0 mm
2
1.0 mm
2
1.0 mm
2
0.75 mm
2
2
2
Cable colours
bl
br
ge
gn
gr
or
rt
sw
vi
ws
Blue
Brown
Yellow
Green
Grey
Orange
Red
Black
Violet
White
Item Designation Comment
A1 Heater
A2 Control unit
B1 Flame monitor
B2 Temperature sensor
B3 Temperature limiter/
overheating guard circuit
B4 Cabin thermostat
E Glow plug
F1 20 A fuse Blade-type fuse SAE J 1284
F2 5 A fuse Blade-type fuse SAE J 1284
F3 20 A fuse Blade-type fuse SAE J 1284
H1 “Heating” symbol in the display Operating indicator (in item P2)
H3 Symbol light Light (in item P2)
H6 Red LED Light in immediate heat button, ready
indicator, switch-on indicator
(in item P2)
K5 Relay For vehicle fan
M1 Motor Combustion air fan
M2 Motor Circulating pump
M3 Motor Vehicle fan
Item Designation Comment
P2 Standard clock For programmed operation
S8 Momentary-contact switch Immediate heat button remote
control
X1 4-pin plug connector To item A2
X2 2-pin plug connector To item A2
X3 2-pin plug connector To item A2
X4 2-pin plug connector To item A2
X5 12-pin plug connector To item A2
X6 12-pin plug connector Diagnosis
X8 12-pin plug connector To item A2 (ST 2)
X9 12-pin plug connector To item P2
X10 2-pin plug connector W-bus diagnosis
X11 12-pin plug connector To Y1
Y1 Metering pump Fuel pump for heater
