Jun-Air 2 OF302-40M Series Operating Manual Download

Page: 9 / 48

Service

Please note that all service must be carried out by a qualified
person.

Adjustment of pressure switch

The working presure has ben preset from the factory, and it is
normally not necessary to change this.
However, if it is necessary to change the preset settings, the
instructions mentioned below should be followed carefully.

Warning!

The compressor is constructed and approved
for a max. pressure as stated under Technical
Specifications - do not adjust to a higher pressure.

Higher working pressure will reduce the lifetime of
the compressor.

The compressor will stop at max. pressure (stop pressure) and
start again at min. pressure (start pressure). The difference
between max. and min. pressure is the differens pressure.

Unscrew the lid of the pressure switch. Adjust max. pressure
adjusting the two springs marked A (clockwise: higher
pressure). Adjust the two springs identically.

Adjust the differens pressure adjusting the spring marked B
(clockwise: higher differens pressure, lower start pressure.

Test of pumping time

The pumping time indicates the condition of the compressor.

Check that there are no leaks in the system.
Empty the air receiver of compressed air so that the
pressure gauge shows 0 bar.
Close the filter regulator and check that the drain valve is
closed.
Start the compressor and note the time it takes until it is
turned off again by the pressure switch. Check that the
pumping time agrees with the technical specifications for
the actual compressor system.

Please note that the pumping time in this manual is given for 0
to max pressure. Deviations from this result in deviating results.

Important!

Always test the pumping time when cold. If the
compressor is warm, the pumping time will be
considerably longer.

1.
2.

Fault finding and repair

Important

Switch off and isolate from electrical supply before
removing any parts from the compressor. Empty air
receiver of air before performing any operation on the
compressors' pressure system.

1. Compressor does not start

The air receiver is pressurized. The motor will start when
the pressure has dropped to the preset start pressure.
Empty the receiver.
Check that the mains supply agrees with the motor label.
No power from mains. Check fuses and plug.
Bad connection or broken cable.
The motor is overheated and the thermal protection
has switched it off. When cooled the motor will turn on
automatically. Go to section 5.
The compressor has not been unloaded and there is back
pressure on the piston. Ensure that the compressor is unloaded
each time it stops.
The motor is blocked.
Defective capacitor.

2. The compressor makes a buzzing sound but does not start

Leaky non-return valve. Dismount the pressure pipe and
check if air leaks from the non-return valve. Clean and
replace.
The motor is blocked.

3. The compressor runs but the pressure does not increase

Intake filter clogged. Replace.
Non-return valve is clocked. Clean or replace.
Leaks in fittings, tubes or pneumatic equipment. Check with
soapy water or by letting unit stay over night disconnected
from mains. Pressure drop should not exceed 1 bar.
Check the piston gaskets. Replace if necessary.
Defective valve plate. Contact your JUN-AIR distributor.

5. The motor gets very hot

The ambient temperature is too high. If the motor is installed
in a cabinet sufficient ventilation must be ensured.
Leaks in fittings, tubes or pneumatic equipment. Check with
soapy water or by letting unit stay over night disconnected
from mains. Pressure drop should not exceed 1 bar.
The compressor is overloaded.

6. The compressor runs even if no air is tapped

Leaks in fittings, tubes or pneumatic equipment. Check with
soapy water or by letting unit stay over night disconnected
from mains. Pressure drop should not exceed 1 bar.

7. The compressor does not start at min pressure or does

not stop at max pressure.

Defective pressure switch. Replace.

b.
c.
d.
e.

g.
h.

a.
b.
c.

d.
e.