Refrig compressors are considered "low torque". They will
typically only start if the pressure on suction and
discharge sides are equal. Sounds like you need a high
torque compressor, or a hard start kit.

--
Christopher A. Young
Learn more about Jesus
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On Sep 25, 6:31 am, "Dennis"
wrote:
I picked up a small fridge compressor with the idea of
playing around using
it for a vacuum pick up tool for small electronics parts,
but it behaves
strangely.

On initial power up it runs fine, very quietly.

It quickly/easily pulls down to 20kpa (-80kPa).

However if I disconnect the power and reconnect there is a
quiet hum like
the motor is stalled (motor is not running & there is no
airflow).

If I disconnect again then wait a minute or two before
reconnecting it
powers on fine and will run fine - I've let it run for 5
minutes
continuously with no problems.

As part of the terminals to the motor there appears to be
a thermal overload
switch, it gets warm but not hot (my guess ~30 Celius)

Heres a link to the data sheet:

http://www.transtech-co.jp/electroni...ompressor7.pdf

I vaguely recall something about fridges having protection
against rapid
cycling of the power for some reason - but that could be
rubbish. If there
is some sort of anti-short cycle timer it must be inside
the compressor
housing itself.

Any ideas?

Thanks.