- Question Title: My compressor will not load air when pressure switch is turned on
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- Answers: 1
My Atlas Copco XAS375JD3 Truck towed compressor will not load air when the pressure switch is turned on.
The machine comes up but when you press down the pressure switch the air does not load.
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Hello,
Unfortunately, I don't have any manual for the XAS375Jd compressor, but I have included a picture of a XAS405Md (a little bit bigger, and with Mercedes engine instead of John Deere). But the control system should be about the same.
With pressure switch, you mean the button that says "LOAD", when you press it down, the compressor goes to LOAD condition. Right?
Please see the picture above.
With the portable compressors of Atlas Copco, both the engine speed and the air intake of the compressor are controlled. When the compressor is started air intake is closed and the engine runs in IDLE speed (low speed).
The compressor runs in "unloaded" condition.
You can see the engine speed control and the air intake valve on the picture (I added big red text).
the air intake valve and the engine speed is closed because air pressure ( from the receiver RED LINES)is directly applied to the intlet valve and speed controller (ORANGE LINES).
When (after warm up of the engine) the switch "LOAD" is pressed, the air through this LOAD button is cut-off. (ORANGE pressure disappears).
The engine speed and intake valve is now controlled by the control valve (top right), through the GREEN lines.
In your case, there can be a few things:
If both engine speed stays Idle and inlet valve stays closed, the LOAD button is broken or dirty. You can replace it or open it and clean it.
If engine speed stays idle, but the intake valve opens, the speed controller is broken or dirty.
If the engine speed does increase (full speed), but still no air is being pumped, it means that the inlet valve is still closed. Check the inlet valve. (beware of the big powerful spring when opening it).
You can check a few things by doing the following:
remove the air connection to the speed control piston. The bar should move to MAX and the engine should go to full speed. If this happens, speed control is OK.
Remove the connection to the inlet valve. The valve should open and the compressor should start building up pressure. If this happens, inlet valve is OK.
Remove connection to LOAD button. Both engine speed should go up and inlet valve should open.
Always be careful when checking things like this, to check for only a short time and with open air outlet valves, as otherwise the pressure might rise too high.
Good luck and if you need any more help, just let me know.