Viessmann VITOCAL 250-A - Page 159

159
F.1012 Fault, low pressure sensor, refrigerant circuit
F.1012
System characteristics
Refrigerant circuit off
Cause
■
Fault, low pressure sensor
■
Further messages: A.82, A.94
Measures
1. Check the low pressure sensor and connec-
tions X14.4 to X14.6 on the VCMU refrigerant circuit
controller:
■
Check wires and plugs for correct seating.
■
Check connections for contact corrosion.
■
Check cables for mechanical damage, e.g. crush-
ing, kinking, chafing or breakage.
2. Check voltage between X14.5/X14.6 in system
operation. If it deviates from the curve, replace the
low pressure sensor.
3. Replace VCMU refrigerant circuit controller.
F.1034 Communication fault, external CAN bus
F.1034
System characteristics
Limited normal operation
Cause
■
Short circuit, external CAN bus
■
Connections 91.CAN L/91.CAN H interchanged
Measures
1. Turn off the ON/OFF switch on the indoor unit. Wait
at least 2 min. Turn on the ON/OFF switch.
2. Check configuration for correct HPMU electronics
module.
3. Check the following CAN bus connections:
■
Connection X8.1 to X8.3 on plug 91 on
HPMU electronics module
■
Wall mounted indoor unit:
6-pole connection socket on underside of appli-
ance on left, terminals 91.CAN L to 91.CAN H
Floorstanding indoor unit:
Luster terminals for bus connections, terminals
91.CAN L to 91.CAN H
■
Check wires and plugs for correct seating.
■
Check connections for contact corrosion.
■
Check cables for mechanical damage, e.g. crush-
ing, kinking, chafing or breakage.
■
Check CAN L/CAN H assignment.
■
CAN Ground (GND) must not be connected.
■
Check cable type: Li2YCYv, twisted pair, shielded
or 2-core CAT5, shielded
■
Check cable length.
■
Check the position and number of terminators.
4. Replace CAN bus cable.
5. Replace HPMU electronics module.
Messages
Fault messages (cont.)
6218234
Diagnosis