Viessmann VITOCAL 250-A - Page 182

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A.100 Settings deleted
A.100
System characteristics
Settings on the heat pump control unit deleted
Cause
Data memory on the electronics modules faulty
Measures
1. No action required
2. If the message appears often: Replace electronics
modules.
A.101 Hot gas temperature not plausible
A.101
System characteristics
Refrigerant circuit operation impaired
Cause
Values for hot gas temperature in relation to hot gas
pressure not plausible
Measures
1. Check high pressure sensor:
With the system running, measure the voltage U
from 0 to 5 V at connection X14.2/X14.3 of the
VCMU refrigerant circuit controller.
If it deviates from the curve, replace the high pres-
sure sensor.
2. Check hot gas temperature sensor:
Check resistor R for NTC 10 kΩ on the disconnected
plug. Replace sensor if required.
Connection: X14.9/X14.10 on the VCMU refrigerant
circuit controller
A.102 Suction gas temperature not plausible
A.102
System characteristics
Refrigerant circuit operation impaired
Cause
Values for suction gas temperature in relation to suc-
tion gas pressure not plausible
Measures
1. Check low pressure sensor:
With the system running, measure the voltage U
from 0 to 5 V at connection X14.5/X14.6 of the
VCMU refrigerant circuit controller.
If it deviates from the curve, replace the low pres-
sure sensor.
2. Check hot gas temperature sensor:
Check resistor R for NTC 10 kΩ on the disconnected
plug. Replace sensor if required.
Connection: X14.7/X14.8 on the VCMU refrigerant
circuit controller
A.109 Actual boiler temperature too low
A.109
System characteristics
■
Heat pump temporarily off
■
Heat provided by external heat generator is insuffi-
cient
Cause
Actual boiler temperature too low
Measures
1. Check connections and plug-in connection at TS2.1/
TS2.2 on HIO electronics module.
2. Check resistor R for NTC 10 kΩ on disconnected
plug.
3. If fault occurs frequently, check following settings:
■
For external heat generator
■
For secondary circuit
Installation and service instructions for external
heat generator and associated control unit
Messages
Warning messages (cont.)
6218234
Diagnosis