Viessmann OC208HM, Service Instructions For Contractors

Page: 27 / 48

Fault Possible cause Measures
Compressor can-
not function Power supply line break Check power supply for short
circuit or earth fault. Check
fuses
High pressure switch has
tripped Locate and remove the rea-
son for the tripping. Reset
the high pressure switch and
restart the unit
Control fuse blown Check control circuit for
short circuit or earth fault.
Check the fuse
Core(s) of the supply cable
loose Secure cores at the term-
inals
Wiring incorrect Check the wiring of the con-
trol and safety equipment
Supply voltage too low Check the on-site installation
(e.g. cable cross-sections). If
no on-site causes can be es-
tablished, inform the relevant
power supply utility
Compressor motor short
circuit Check the motor winding for
continuity
Compressor seized Replace compressor
Low pressure
switch is tripped
and switches the
unit off Refrigerant leak Identify and repair leak
Inadequate refrigerant fill-
ing Top up refrigerant
Low pressure switch faulty Replace low pressure switch
High pressure
switch is tripped
and switches the
unit off High pressure switch Replace high pressure
switch
Gases in the refrigerant cir-
cuit that cannot be com-
pressed Vent the refrigerant circuit
Fan failed Check supply cable and fan
motor and replace, if re-
quired
Liquid line too hot Inadequate refrigerant fill-
ing Determine and remedy the
cause for the refrigerant loss;
top up with refrigerant
Liquid line frosted
over The shut-off valve in the li-
quid line is partially closed Check whether all valves in
the refrigerant circuit are
open
Filter dryer blocked Replace the filter dryer
Diagnosis
(cont.)
27
Troubleshooting
5692
695
GB