Viessmann VITOCAL 300-G Installation And Service Instructions Manual page 165

No display indication on the programming unit
5. Replace programming unit if
required.
Repairs
Overview of internal components
U
T
S
R
Q
P
O
N
M
L
K
A Primary circuit flow temperature
sensor (heat pump brine inlet)
B Suction gas temperature sensor
C Condenser
D High pressure sensor EEV
E Secondary circuit flow temperature
sensor
F Compressor
6. Replace controller and sensor PCB if
A B C E D F
G Secondary circuit return tempera-
H Drain valve on the secondary side
K Sight glass
L Electronic expansion valve (EEV)
M Drain valve, primary side
N Filter dryer
(cont.)
required.
F G
H
ture sensor
Troubleshooting
165