Danfoss DHP-AX Installation And Service Instructions Manual page 55

Problem – Loud compressor noise
Cause
1. Phase drop.
The compressor attempts to start
or operates on two phases.
2. Touching pipes – vibrations.
3. Compressor fault.
Problem – Shrieking whistling noise
Cause
1. Whistling expansion valve.
2. Noise from the soft-starter.
3. The compressor's IPR valve
opens.
Problem – Noise – miscellaneous
Cause
1. Vibrating protective sleeves on
the pressure switches.
2. Vibration noise from the elec-
trical installation.
3. The heat pump is not level.
Troubleshooting
1. Check that there is 400 V between
incoming phases on the heat pump.
2. If there is supply to the heat pump,
measure the voltage for all electrical
components all the way to the compres-
sor, see wiring diagram.
Establish which pipe(s) is/are causing the
problem.
Determine whether the compressor is
unusually loud.
Troubleshooting
1. Take overheating readings, adjust to
the recommended value.
2. Open and close the valve fully in and
out.
3. Adjust the expansion valve to recom-
mended overheating value again.
Measurement check the input and out-
put phases for the soft-starter as well as
the control signals from the I/O card, see
wiring diagram.
The compressor has an integrated IPR
valve that opens at 28 ±3 bar.
When the valve opens, pressure equalizes
between the compressor's high and low
pressure side and a milling/whistling
sound is heard.
To establish whether the valve opens at
the correct pressure, connect a manome-
ter on the high and low pressure side.
When the valve opens, this is indicated
by the pressure on the low pressure side
rising and reaching the pressure on the
high pressure side.
Check at what pressure the valve starts
to open.
Troubleshooting
Establish where the vibration noise is
coming from.
Check for electrical steps or similar devi-
ces screwed to the heat pump and wall.
These can cause vibrations and noise.
Check that the heat pump is level by
using a spirit level.
Check that the heat pump is supported
by all four feet
VMBMH302
Remedy
Check where the phase drop is and rec-
tify.
Try to release any tensions that cause the
vibrations.
If the compressor is defective, replace it.
Remedy
Check if the noise has stopped, if not,
continue with point 2.
Continue with point 3.
If the problem persists, replace the
expansion valve.
If the soft-starter is defective, replace it.
If it opens at a too low pressure, replace
the compressor.
Remedy
Prevent the protection sleeve vibrating
by using insulation tape for example.
Carry out according to the installation
instructions.
If the heat pump is not level, adjust using
the feet.
Service – 55