Viessmann VITOTRONIC 200 Service Instructions Manual page 65

Messages
(cont.)
Message
Code/system characteris-
tics
DB Refrig. circ. (SHD) 2
Compressor stops.
DC Low pressure 2
Compressor stops.
Cause
Refrigerant circuit fault,
heat pump stage 2
(if installed):
■ Safety high pressure
switch has responded.
■ Compressor motor
overload relay (thermal
relay) has responded.
■ If installed:
Separate compressor
motor overload relay
has responded.
Low pressure fault, heat
pump stage 2
(if installed):
■ Heat pump faulty.
■ Primary pump faulty.
■ Low pressure sensor
has detected a fault or
is faulty.
Troubleshooting
Measures
■ Check flow and return
temperature sensors in
primary and secondary
circuits.
■ Check primary and sec-
ondary circuits for pres-
sure and throughput
(see also message A9).
■ Have heat pump tested
by a refrigeration engi-
neer.
Switching signal can be
tested at terminal 214.2
(see page 150).
Note
After removing fault,
switch appliance OFF and
ON again once.
■ Have heat pump tested
by a refrigeration engi-
neer.
■ Check pressure gauge,
primary pump and shut-
off facilities.
■ Check low pressure
sensor, lead and EEV
PCB, and replace if
required.
Signal from plug aYH can
be tested at connection
214.3 (see page 150).
65