Danfoss Heat Pump Troubleshooting Manual page 4

Troubleshooting Guide
Hot gas temperature too high
See in service under heat pump also check using own digital thermometer.
Action:
Check the refrigerant circuit see section below
The discharge pipe sensor displays correctly but still has high overheating
Action:
Using manometer apparatus and a digital thermometer check what the cooling and overheating reading of the unit is.
Also check that bulb and capillary tube are undamaged and that the bulb is correctly positioned. (Bulb is positioned at two o'clock in
the suction pipe).
If the cooling is correct according to the instructions try adjusting the overheating using the expansion valve, if the overheating cannot
be adjusted using the expansion valve or if the capillary tube or bulb are damaged replace it.
Lack of refrigerant, not enough refrigerant in the hp cooling circuit.
Action:
Using manometer apparatus and a digital thermometer, check that the unit's cooling and overheating is correct for the specific
refrigerant.
If cooling is not at the correct level compared with the specific refrigerant and is too low, there is insufficient refrigerant in the unit.
If there appears to be a leak in the refrigerant 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 bubbles.
Also check if oil has leaked. In event of leakage oil usually comes from the refrigerant circuit.
4
Working pressostat and high pressure pipe
Discharge
pipe sensor
location
150 ohm sensor
Outdoor / Defrost sensor
temperatur ohm
-30 1884
-25 1443
-20
-15
-10
-5
0
5
10
15
20
25
30
35
40
VMIFB202
22 kohm sensor
Supply line, return line, hot water,
brine in, brine out, discharge pipe sensor
temperatur kohm
0
5
1115 10
868 15
681 20
538 25
428 30
343 35
276 40
224 45
183 50
150 55
124 60
103 65
86 70
75
80
85
66.3
52.4
41.8
33.5
27.1
22
18
14.8
12.2
10.1
8.5
7.1
6
5
4.2
3.7
3.1
2.7