# Compressor won't start



## Think3D (Aug 15, 2014)

I have one of the 7.5 horse Campbell Hausfeld rigs that puts out about 28 [email protected] psi. The motor turns on but the compressor drivewheel barely moves. I have been letting in sit for awhile for the air to leak down in the head, then the thing will kick on. This has been going on for a long time and I have contacted CH, bought and installed a new unloader at the pressure switch. That did not solve the problem. I also cleaned the valve located where the compressor discharge enters the tank. I have now allowed the compressor several days to ''leak down'' and it still won't kick on. The motor hums and turns the wheel slow as it has been doing. Any ideas? Thanks!
Wayne


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## CompressorPros.com (Jun 27, 2014)

Have you checked to see if the compressor pump turns relatively freely without the belt? It is possible that it is at least partially locked up. With, what I assume are aluminum pistons, or at least the low pressure piston. It can run and get hot enough to lock up and when it cools, the aluminum compresses enough to free up. Other than that, could be the motor.


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