Viessmann VITOCAL 151-A Installation And Service Instructions Manual page 111
Air source heat pump, monoblock version for heating and cooling operation, with 1 integrated heating/cooling circuit
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Also See for VITOCAL 151-A:
- Operating instructions for the system user (60 pages) ,
- Manual (24 pages)
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Fault messages
(cont.)
Message code
System characteristics
F.985
The refrigerant circuit will not
start.
F.990
Secondary circuit not control-
led
F.991
Secondary circuit not control-
led
F.992
No heating/cooling of exter-
nal heating water/coolant buf-
fer cylinder
F.993
No heating of external heat-
ing water/coolant buffer cylin-
der
F.994
No heating of external heat-
ing water buffer cylinder
F.995
No heating of external heat-
ing water buffer cylinder
Cause
Control of electronic ex-
pansion valve 2 faulty
Short circuit, temperature
sensor
Lead break, temperature
sensor
Short circuit, temperature
sensor of external heating
water/coolant buffer cylin-
der
Lead break, temperature
sensor of external heating
water/coolant buffer cylin-
der
Short circuit, temperature
sensor of external heating
water buffer cylinder
Lead break, temperature
sensor of external heating
water buffer cylinder
Troubleshooting
Measures
Check connections on VCMU re-
■
frigerant circuit controller.
Isolate the system from the pow-
■
er supply. Restart the system.
If the fault persists, replace the
VCMU refrigerant circuit control-
ler.
Check the settings in the com-
■
missioning assistant. Adjust set-
tings if required.
Check resistance value
■
(NTC 10 k
) at connection X17
Ω
of the EHCU electronics module.
Replace sensor if required.
Check the settings in the com-
■
missioning assistant. Adjust set-
tings if required.
Check resistance value
■
(NTC 10 k
) at connection X17
Ω
of the EHCU electronics module.
Replace sensor if required.
Check the settings in the com-
■
missioning assistant. Adjust set-
tings if required.
Check resistance value
■
(NTC 10 k
) at connection X17
Ω
of the EHCU electronics module.
Replace sensor if required.
Check the settings in the com-
■
missioning assistant. Adjust set-
tings if required.
Check resistance value
■
(NTC 10 k
) at connection X17
Ω
of the EHCU electronics module.
Replace sensor if required.
Check the settings in the com-
■
missioning assistant. Adjust set-
tings if required.
Check resistance value
■
(NTC 10 k
) at connec-
Ω
tion X17.1/X17.2 of the EH-
CU electronics module. Replace
sensor if required.
Check the settings in the com-
■
missioning assistant. Adjust set-
tings if required.
Check resistance value
■
(NTC 10 k
) at connec-
Ω
tion X17.1/X17.2 of the EH-
CU electronics module. Replace
sensor if required.
111
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