Table 13.
Problem – Operating pressure switch open alternatively high hot gas temperature
Cause
Troubleshooting
Remedy
1. Operating pressure switch, func-
tion.
1.
Switch off the main switch for the
heat pump, wait until the com-
pressor has been stationary for at
least 15 minutes.
2.
Disconnect the two cables on the
pressure switch, using a buzzer
check if the pressure switch is
closed.
If the pressure switch is closed, bridge
the pressure switch cables temporarily
and switch on the voltage to the heat
pump again. If there is an indication 0
(zero) in the display this means that the
pressure switch is fault-free and the
problem is in the wiring or in the circuit
board.
If the pressure switch is open, try care-
fully tapping the head of the pressure
switch with a screwdriver and use a buz-
zer test to see if it has closed again.
Replace the pressure switch if it appears
to jam repeatedly.
2. Fault in the discharge pipe sensor.
Check what the discharge pipe sensor
shows. Is it a plausible/actual value?
Measure the resistance of the discharge
pipe sensor, check against the ohm table
in Measurement points, Page 11.
If the discharge pipe sensor is defective,
replace it.
3. Hot gas temperature too high.
The discharge pipe sensor displays more
than 140°C. See operating data.
The square symbol appears when the
delivery pipe temperature is as high or
greater than the maximum temperature
of the discharge pipe 140°C.
4. Lack of refrigerant, not enough
refrigerant in the system.
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. If leak
tracer is not available, brush soap water
on the suspected leak and look for bub-
bles. Also check for oil as this can come
out from the refrigerant circuit.
3.5.2
Leakage
Table 14.
Problem – Leak fluid side
Cause
Troubleshooting
Remedy
1. Insufficiently tightened connec-
tions.
Locate the leak.
•
Tighten the connection and check
that it is sealed.
•
If it is still not sealed, replace the
entire connection and support
sleeve (only at soft pipes).
2. Defective gasket or O-ring.
Locate the leak.
Replace the gasket or O-ring.
3. Cracked nut or connection.
Locate the leak.
Replace nut or connection.
4. There is no overflow pipe connec-
ted to the safety valve(s).
Establish which safety valve does not have
an overflow pipe.
Install an overflow pipe according to the
applicable norms.
5. Filler valve between incoming cold
water and heating system not closed
or leaking.
Check whether water continuously leaks
from the safety valve on the expansion ves-
sel on the hot side.
Try closing the filler valve and see if
water stops dripping from the safety
valve. If not, replace the filler valve.
20 – Service instructions VMGFJ102