RH SERIES—HIGH TEMPERATURE SECTION 2
32
2.14 TROUBLESHOOTING
 IMPORTANT
Before starting maintenance activity or repair 
on the dryer, the main power switch and ON/
OFF switch must be turned OFF. Also, the 
compressed air must be vented from the sys-
tem and the inlet and outlet valves must be 
closed. The dryer has to be isolated com-
pletely.
PROBLEM POSSIBLE CAUSE REPAIR COMMENTS
Dryer-on light is  lit but 
refrigerant compressor is 
not operating
cont.
Refrigeration unit is not 
operating
Check refrigeration com-
pressor
Several factors may cause compres-
sor failure. 
A qualified refrigeration contractor 
should check all electrical and refrig-
erant control
The refrigerant high pres-
sure protection has 
tripped 
The refrigerant safety 
high pressure switch has 
tripped 
The dryer is protected against a very 
high refrigerant pressure. It will trip in 
case the condenser efficiency is 
reduced 
Manually reset the switch (green but-
ton) 
Excessive ambient tem-
perature
Ensure that dryer inlet 
conditions are within the 
recommended range. 
Designed conditions and 
correction factors are 
described in product liter-
ature.
A high ambient temperature may 
cause the refrigerant system to oper-
ate at higher than normal pressures. 
Results will be a higher than normal 
evaporator temperature.
Important: there should be adequate 
air circulation around the dryer, and 
proper ventilation in the equipment 
room is a must to achieve a low 
enough ambient temperature
Excessive temperature 
on crankcase of com-
pressor 
Allow time for the com-
pressor to cool down
Reason may be a possi-
ble incorrect adjustment 
or shortage of refrigerant
Compressor is protected against too 
high a temperature of the crankcase 
by a thermal switch called “klixon”
Klixon can be located internally to 
refrigerant compressor or under the 
protective cover on the top of the 
compressor
Excessive compressed 
air inlet temperature
Be sure that dryer inlet 
conditions are within the 
specified range. 
The dryer is designed for working 
within calculated maximum condi-
tions.
Should these conditions change, the 
dryer can be overloaded,  the dew 
point will go up and protecting devices 
can switch off