36
Red LED on the heat pump control unit
A
Fig. 25
A
Red LED
Red LED
Cause
Measure
Flashes briefly
every 10 s.
No fault
No action required
Flashes in a dif-
ferent se-
quence.
Fault
See message on the programming unit
Constantly off
No power supply
Restore power supply.
Messages on the programming unit
Message
Cause
Measure
"ER 0"
Programming unit faulty
Replace programming unit.
"ER 1"
Safety high pressure switch has responded.
Overpressure in the heat pump circuit.
Switch power supply OFF and ON again.
Or
Acknowledge message. See the following
chapter.
"ER 2"
High limit safety cut-out has responded.
Overheating of the DHW cylinder.
Ensure DHW is being drawn.
Reset high limit safety cut-out (see
page 39).
"ER 3"
Short circuit/lead break, top cylinder temperature
sensor (NTC1)
Check resistance value and replace sensor
if necessary (see page 41).
"ER 4"
Short circuit/lead break, air intake temperature
sensor (NTC2)
"ER 5"
Short circuit/lead break, evaporator temperature
sensor (NTC4)
"ER 6"
Short circuit/lead break, bottom cylinder temper-
ature sensor (NTC3)
Troubleshooting
Messages
6136003
Diagnosis
