Viessmann Vitocal 350-A Installation And Service Instructions Manual page 148

Troubleshooting
Control unit diagnostics
Message
System characteristics Cause
«CF Communication module
«D1 Compressor
148
(cont.)
Communication error -
LON module in heat
pump control unit
Compressor fault:
Thermal compressor
relay or safety element of
full wave soft starter (if
installed) has respon-
ded.Separate compres-
sor motor protection (if
installed) has responded
Measures
Check LON communica-
tion module and replace if
required.
If required, replace in the
following order: PCB 3,
ribbon cables between
PCB 3 and 2, PCB 2.
■ Reset compressor ther-
mal relay, check setting,
restore delivered condi-
tion ("Reset", see oper-
ating instructions).
Check compressor
electrical connections,
test coil resistance of
compressor motor.
Check compressor
phase sequence.
The switching signal (of
thermal relay, full wave
soft starter, separate
motor protection) can
be tested at terminal
1X5.9 (230V).
Note
If overheating occurs,
internal motor protection
prevents a re-enabling of
the compressor for 1-3
hours.
■ If required, replace full
wave soft starter (if
installed); have com-
pressor checked by
refrigeration engineer.