Viessmann Vitoclima 300-S Service Instructions For Contractors page 29

Diagnosis
(cont.)
Mains voltage
The mains voltage must be between
198 and 264 V~.
Main fuse/MCB (20 A)
If the fuse has blown:
Check the compressor, fan and other
components that may be able to
cause a short circuit.
Choke coil
Check the connections of the choke
coil.
Separate the coil from the controller
and check the coil cable for continuity.
External fan
Check the connections (check the
power supply and speed sensor).
Ensure the fan rotates freely. The fan
must be able to be turned easily by
hand. Replace the motor if the motor
bearings have seized up.
If the fan can rotate freely, the AC
power consumption of every phase
must be below 1 A.
Compressor
Check the compressor connections.
The AC power consumption of each
phase must be lower than 15 A.
If no current flows, check the resis-
tance between the three poles.
Changing fuses.
If the fuse blows regularly, replace the
controller.
Check for a short circuit between the
coil wire and the metal core.
If the fuse is OK, replace the control-
ler.
If no current flows, check the resis-
tance between the three poles.
The three winding resistances should
be approximately the same. The stan-
dard value would be between 10 and
20 .
Switch the equipment to standby or
OFF and then ON again. If the pro-
blem persists, replace the controller.
The three winding resistances should
be approximately the same. The stan-
dard value would be between 0.8 and
1.5 .
Switch the equipment to standby or
OFF and then ON again. If the pro-
blem persists, replace the controller.
Troubleshooting
29