Viessmann Vitocal 300-G BW, Installation And Service Instructions Manual

Page: 120 / 216

120
ID Message (pri-
ority) 1. Cause
2. Measures Access right
A9 Heat pump
("
U
")
1. Safety high pressure, control high pres-
sure 10 times in sequence/
≥
24 h
period, fault refrigerant circuit control,
all primary/secondary temperature
sensors faulty, low pressure response
10 times in sequence
2. Message history: Scan further mes-
sages (page 113), check flow rates,
check motor currents/motor protection
switch, check safety high pressure lim-
iter
Note
Switch appliance off and on after remov-
ing the cause for the message.
Customer
EXT Electric heating
("
U
") Danger
Touching 'live' components in the
working area can result in the
transfer of dangerous body cur-
rents.
Ensure the device is at zero volts
before carrying out the instanta-
neous heating water heater or
prior to resetting the high limit
safety cut-out.
1. Instantaneous heating water heater
faulty or high limit safety cut-out has
responded
2. Check the instantaneous heating water
heater and the high limit safety cut-out
and reset, if required.
(see instantaneous heating water
heater installation instructions)
Customer
AD Mixer heating
DHW ("
U
")
1. Three-way valve faulty
2. Check the three-way valve and
replace, if required
Customer
Troubleshooting
Control unit diagnostics
(cont.)
5368 522 UAE