# Atlas Copco KT4A5 compressor - help



## Vikerlund (10 mo ago)

Hello, I have recently inherited an Atlas Copco KT4A5 compressor. The unit has been in use not very often. When installed (25 + years ago) the unit was refitted by a company working with compressors and has performed problem free. I have been using the unit from Oct 21 and observed that when started, the unit would build up pressure (as normal) and shut off at the preset max pressure. (as normal) Problem is when using the air, the unit does not start again when the lower level for auto start is reached. The unit won't start at all. Have to wait a day. If I start the unit and manually stop the unit before the shut-off pressure is reached, then I have no problem restarting the unit manually again..... Any ideas of the cause, fix?

Seen a refitted (identical) unit on youtube with updated electrics that appear really tidy and compact and this would be the direction I would like to go down the road.... Link 

Appreciate any help....

Paul


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## iowagold (Jan 22, 2020)

pretty basic on the controls for these units.
to work on them you need to be real good with a test light and a VOM.
if those check boxes are ticked...
then yea check every thing!

they are known for issues with sensors...
pressure, low oil, oil pressure (on the engine models), temp sensors...
with that in mind place the test light in the right spots to check the sensors while live.

light bulbs also work!
just use the right voltage and low wattage bulbs like 2 watt and below across the sensor contacts.
led is best is some parts of the circuits.

also check the start box.
i had a start box this last week with the thermal fuse that the thermal fuse was out of range at times.
nice 20.00 fix on that one!


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