Viessmann VITOTRONIC 200 Service Instructions Manual page 89

Diagnosis (service scans)
Line "CTT, ICT, IRT [°C]"
Col- Explanation
umn
2 Compressor head temperature (CTT).
3 Condensation temperature, condenser (ICT).
4 Liquid gas temperature (IRT).
Line "HST, LWT, RWT [°C]"
Col- Explanation
umn
2 Heat sink temperature, DC inverter (HST).
3 Secondary circuit flow temperature upstream of instantaneous heating
water heater (LWT).
4 Secondary circuit return temperature (RWT).
Line "pHI, pLO, EEV [–]"
Col- Explanation
umn
2 Status of high pressure switch (pHi) (if installed):
"1" Not responded or not instal-
led.
3 Status of low pressure switch (pLO):
"0" Not responded or not instal-
led.
4
Position of electronic expansion valve (EEV), value range 0 (≙ fully closed)
to 480 steps (≙ fully open).
Line "A [–]"
Col- Explanation
umn
1 Refrigerant circuit fault:
"0" No fault:
"1" Short circuit/lead break, con-
denser temperature sensor
(ICT).
"2" Short circuit/lead break, liquid
gas temperature sensor
(IRT).
(cont.)
"2" Responded.
"1" Responded.
"3" Short circuit/lead break, sec-
ondary circuit flow tempera-
ture sensor (LWT).
"4" Refrigerant circuit fault, inter-
nal unit active.
Troubleshooting
89