Cause
Troubleshooting
Remedy
12. Blocked condenser on the water
side.
If there is no strainer in the heating sys-
tem, there is a risk of dirt sticking in the
condenser and blocking it. Unfortunately
there is no easy way of checking if the
condenser is blocked.
You can carry out a test by allowing the
compressor and circulation pumps to
remain in operation and after a while,
check that the pressure pipe becomes hot
and that the circulation pumps work (for
circ.pumps with a bleed screw, unscrew it
and feel if the pump rotor rotates using a
screwdriver).
Then read the temperature on both con-
nection pipes to the condenser:
If the temperature difference is <3°C, the
condenser is probably blocked.
If the temperature difference is 3-13°C, it is
probably not blocked.
If the temperature difference is >13°C, the
condenser is probably blocked.
If the condenser is thought to be
blocked, try flushing it. If this does not
work, it must be replaced
13. Blocked condenser on the refriger-
ant side.
Using manometer apparatus and ther-
mometer, check that the unit’s overheat-
ing is correct for the specific refrigerant.
If the condenser is thought to be blocked
by oil for example, try blowing nitrogen
through it to release the oil. If this does
not work, it must be replaced
14. Overfilled refrigerant circuit.
Using manometer apparatus and ther-
mometer, check that the unit’s overheat-
ing is correct for the specific refrigerant.
Follow the correct procedure (depend-
ing on type of refrigerant) to add the cor-
rect amount of refrigerant.
If there appears to be a leak in the refrig-
erant circuit, carry out leak tracing and
any necessary corrective action.
Table 8.
Problem – Alarm MS (motor protection)
Cause
Troubleshooting
Remedy
1. Phase drop or blown fuse.
Check the fuses in the fuse box. Check that
all phases are present on the terminal
block for incoming supply. Also check that
all wiring is secure, if screw terminals are
used they must be properly tightened, if
phoenix flat spring terminals are used, the
cables must be secure in the correct hole
with load on the cable.
If any of the phases are missing, check
backwards towards the building’s main
electrical cabinet. If there are no phases
there, contact the network supplier.
2. Cable break.
Check the supply to the motor protection,
soft-starter or compressor.
If a cable is damaged, replace it.
3. Defective soft-starter (three-phase
heat pump).
Measurement check and establish that
when the Heat pump card gives a signal
(there must be voltage between A1 & A2
on the soft-starter), the soft-starter relea-
ses all three phases down to the compres-
sor.
If the soft-starter does not release the
phases when it receives signals from the
heat pump card, replace it.
4. Defective soft-starter (single phase
heat pump).
Check measure and establish that when
the Heat pump card gives a signal (there
must be voltage between ON and N on
the soft-starter), the soft-starter releases
the phases to the compressor.
If the soft-starter does not release the
phases when it receives signals from the
heat pump card and does not alarm as
below, replace it.
Service instructions VMGFJ102 – 17
