Troubleshooting Advice In Case Of Malfunctioning - MIL'S AM 3 Notice D'utilisation

4. TROUBLESHOOTING ADVICE IN CASE OF MALFUNCTIONING
The followings faults may occur during service:
Incident Cause éventuelle

incorrect
The phases were connected back to
direction of
front
rotation

Compressor does No current

not start: Loose cables or fuses

Motor protection switch stopped
compressor

Combistat stopped compressor / is
defective

Connecting cables to
Combistat are defective

Compressor
Too long or too short star‐delta switch
struggles to start
over time

Compressor is under pressure

Fluctuations in the power system

Temperature of the site is too low and
therefore the oil is too viscous

Oil is too viscous

compressor stops
Motor overload has tripped
before reaching
final pressure

Combistat switches off due to high
temperature

Control current is short‐circuited

Motor overload Machine bloquée

stops the
Défaillance des phases

compressor
Surcharge du moteur

Température ambiante trop élevée

Combistat Shortage of oil

operates due to
Oil filter clogged

high temperature
Defective thermostat

Dirty oil cooler

Incorrect installation of compressor

Faulty Combistat or incorrectly set
520513.01
Dépannage

Change the connections of 2 electric
lines

Make current available

Retighten cables and fuses

Unlock motor‐protection switch (in
electric control panel)

Ensure correct cooling, change
Combistat when defective

Ensure correctly fed connecting
cables

Check and reset time period, correct
setting is 3‐6 seconds on relay K1T

Check/change solenoid valve / vent
the compressor

Determine reason

Heat site and compressor or position
in warmer area

Choose suitable oil

Check overload setting and if
necessary alter it. Check setting of
pressure switch, if necessary, alter it.
Check supply of all three phases.

Ensure correct cooling; change
Combistat if necessary.

Remove reason for short‐circuit
and/or replace fuses

Remove reason for seizure

Check supply

Check setting of overload, alter if
necessary, check/alter settings of
pressure switch

Ventilate compressor room

Check and correct oil level

Change oil filter

Change thermostat

Clean cooler (oil and air sides)

Check installation instructions

Adjust or replace Combistat
AM3 – AM55
Incident Cause éventuelle

Safety valve Faulty safety valve

blows
Oil separator cartridge clogged

Oil carryover Dirty oil return (scavenge) pipe

Faulty separator cartridge

High oil level in tank

Compressor was stopped before end
of run‐on time (min 3 minutes)

Compressor does
Setting of pressure switch too high

not vent when
Faulty solenoid

idling; does not
Defective relief valve in suction
stop during
regulator
on/off operation 
Minimum pressure valve jams
i.e. safety valve
blows off

Unit continuously Defective solenoid valve

pressure relieves,
Defective relief valve in suction
reduced flow
regulator

Electrical connection to solenoid
broken

Faulty auxiliary contact on Y‐contactor

No capacity or Air filter clogged

reduced flow
Intake valve faulty or jams

air leaks

Suction regulator Setting cylinder defective, no control
does not close at air

final pressure
Jet is blocked, frozen up

Oil reservoir is Non return valve is faulty
under pressure

Oil contamination
Loose connections in oil circulation
inside cabinet, oil
system

mist on venting
Check seal on oil drain plug

Compressor stops under pressure

Check condition of O‐ring seal at
intake valve and its correct seat

Compressor runs Drive belt not correctly tightened

noisily Drive‐belts are not compatible
matched sets

Pulley discs are not aligned
Dépannage
 Change safety valve
 Change separator cartridge
 Clean scavenge system
 Check/change separator cartridge
 Reduce oil level
 Ensure the compressor is only stopped
after run‐on time has elapsed
 Lower setting of pressure switch
 Change solenoid valve
 Check/change relief valve
 Check/correct minimum pressure valve
 Change solenoid valve
 Change relief valve
 Rectify electrical connection
 Check / change switch
 Change air filter cartridge
 Check suction regulator, butterfly valve,
clean bearing and guide
 rectify leak
 Change setting cylinder and/or solenoid
valve
 Clean jet
 Change non return valve
 Tighten connections
 Tighten screw / replace seal
 Switch off compressor after 3 minutes
run‐on time. Check if run‐on time is 3
minutes or greater
 Change o‐ring if necessary
 Check /adjust tension of drive belt
 Change to compatible matched sets
 Check and correct alignment of drive
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