Viessmann VITOCAL 300-A Installation And Service Instructions Manual page 179

Safety chain, control circuit, main power circuit
G Thermal circuit breaker, fan
H Message input
I Safety high pressure switch
J Low pressure message
K Control high pressure message
L Thermal fuse
M Compressor motor protection (if
motor protection responds, also
check full wave soft starter ther-
mal fuse)
Connection and wiring diagrams
(cont.)
N Compressor relay
O Refrigerant circuit control (con-
troller for electronic expansion
valve EEV)
P Compressor contactor
Y For continuation of safety chain,
see previous illustration
= Plug in cable harness
179