Cause
Troubleshooting
Remedy
6. The compressor runs
backwards.The incoming
phases have the incorrect
sequence (only applies to 3-
phase heat pumps).
If the compressor runs back-
wards, it will not cope with
compressing the refrigerant
and therefore does not pro-
duce the correct power,
which leads to the control
system requesting auxiliary
heating.
▪
If the text ERR PHASE SEQ. appears in the display
when the heat pump is powered, (only appears in the
first 10 minutes) this means that the phases have the
incorrect sequence.
▪
When the compressor is running, check the pressure
pipe temperature by feeling the pressure pipe. If the
phases are correctly sequenced it should be hot (not
just warm) even a distance from the compressor.
▪
When the compressor runs with the phases incorrect-
ly sequenced a strange noise may be heard (loud, rat-
tling) when the compressor runs backwards.
If the phases are in the incorrect order,
switch two incoming phases at the main
terminal block and recheck according to
the troubleshooting window.
7. Changed conditions Have
you increased your heating
and/or hot water demand?
▪
If the heat pump has been dimensioned for a certain
demand and this demand is increased, the heat pump
might not be able to maintain the desired room tem-
perature.
▪
If hot water consumption increases, a larger propor-
tion of time is used to produce hot water, which
means less time for heat production.
If the heat pump cannot cope with the de-
mand, replace it with one with a higher
output or supplement it with a higher out-
put auxiliary heater.
Problem – The auxiliary heater is in operation but not the compressor
Cause
Troubleshooting
Remedy
1. Operating mode AUX.
HEATER is selected.
If this operating mode is selected, the auxiliary heater is
used for heating and hot water production, not the com-
pressor.
If AUX. HEATER mode is selected and you
no longer want it, change to AUTO, the
heat pump then controls both the com-
pressor and auxiliary heater.
2. Peak heat operation (anti-
legionella function) is run-
ning.
Check if the heat pump runs peak heat.
Peak heat operation occurs in connection
with hot water production with the set in-
terval. The compressor should then start to
produce hot water and 2 minutes later the
auxiliary heater starts. The compressor
must then stop and the stop temperature
be reached with only the auxiliary heater
connected. Take no corrective action, this is
normal.
3. The compressor cannot
run due to an alarm.
Check the alarm that is indicated in the display.
Rectify the problem and rest the alarm.
4. The heat pump has stop-
ped on high return.
▪
Check what the MAX value is set at in the heat pump’s
control computer. It must be adjusted to the unit’s
maximum supply temperature and the system’s delta
temperature so that it does not cut at too high a re-
turn temperature when the highest supply tempera-
ture is transmitted.
▪
Check what the return line sensor shows. Is it a plausi-
ble/actual value? If not, take a resistance reading from
the sensors and check against the ohm table in Meas-
▪
If the MAX RETURN value is not adjus-
ted for the system according to the
troubleshooting window, adjust it.
▪
If the sensor is defective, replace it.
Service Instructions
DHP-AQ
Danfoss Heating Solutions
VMGFJ202
29
