Troubleshooting - Rivacold MH-TH Serie Betriebs- Und Wartungsanleitungen

12.

TROUBLESHOOTING

The compressor will not start and no humming sound
is heard
1 No power. Starter relay contacts open.
A
2 Thermal circuit breaker intervention.
3 Electrical connections loose or incorrect.
The compressor will not start (it makes a humming
sound) and the thermal circuit breaker intervenes
1 Electrical connections incorrect.
2 Low voltage at compressor.
3 Faulty start capacitor.
B
4 The relay does not close.
5 Electric motor – winding interrupted or in short
circuit.
The compressor starts but the relay does not open
1 Electrical connections incorrect.
2 Low voltage at compressor.
3 Relay locked closed.
C
4 Excessive discharge pressure.
5 Electric motor – winding interrupted or in short
circuit.
Thermal circuit breaker intervention
1 Low voltage at compressor (three-phase motor –
phase imbalance).
2 Thermal circuit breaker faulty.
3 Faulty run capacitor.
4 Excessive discharge pressure.
D
5 High suction pressure.
6 Compressor overheated - hot return gas.
7 Electric motor – winding interrupted or in short
circuit.
The compressor starts and runs at brief operating
cycles
1 Thermal circuit breaker.
2 Thermostat.
3 High-pressure
insufficient condenser cooling.
E
4 High-pressure switch intervention due to excess
refrigerant gas charge.
5 Low-pressure
insufficient refrigerant gas charge.
6 Low-pressure
expansion valve restriction or blockage.
Likely cause
switch intervention
switch intervention
switch intervention
1 Check the line or replace the relay.
2 Check the electrical connections.
3 Tighten the connections or reconnect
wiring according to the wiring diagram.
1 Make the connections again.
2 Find and remove the cause.
3 Find the cause and replace the capacitor.
4 Find the cause and replace the relay if
necessary.
5 Replace the compressor.
1 Check the electric circuit.
2 Find and remove the cause.
3 Find and remove the cause.
4 Find the cause and replace the relay if
necessary.
5 Replace the compressor.
1 Find and remove the cause.
2 Check characteristics and replace if
necessary.
3 Find and remove the cause.
4 Check the ventilation and any restrictions
or obstructions in the system circuit.
5 Check the sizing of the system. Replace
the condensing
powerful one if necessary.
6 Check the refrigerant charge; repair any
leaks and add gas if necessary.
7 Replace the compressor.
1 See the previous point (thermal circuit
breaker intervention).
2 Small differential: correct adjustment.
due to 3 Check the correct operation of the fan
motor or clean the condenser.
4 Reduce the refrigerant charge.
due to 5 Repair any leaks and add refrigerant gas
if necessary.
due to 6 Replace the expansion valve.
Remedy
unit with a more
MH TH Pag. 25 REV. 08 11/07
UK