I have an IR T 30 compressor that I bought new in 2001 and it has been in pretty much continuous service since then without a single hiccup until now. The breaker is is tripping and the motor cannot get the compressor underway.

I removed the pulley safety guard and the drive belt and started it up. The motor runs fine with no load and does not trip the breaker.

I can turn the compressor pulley by hand so it is not seized up and when I turn it I hear a very satisfying “blurp” sound on one stroke, but not on the second. And it feels like there is some resistance on the silent stroke.

Ingersoll Rand T-30 model 10T air compressor

Ingersoll Rand T-30 model 10T air compressor. This is not Peter’s T30, but this image is here to show you what one looks like as Peter did not upload an image.

Since I never did this test prior to the failure I don’t know what “normal” is, but when I reinstall the belt and turn the motor on it will try to spin up for a few seconds and then trip the breaker again. So, it seems to me that the problem is not with the motor, but with the compressor itself.

I would appreciate any help or suggestions before I haul it off to a service center as I’ve looked all over, but haven’t found the answer to my problem. Bill, thank you in advance.  and thanks for your wonderful and informative site. This comes in from Peter R.

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First, you are welcome. Glad you found my site is informative, Peter.

I do believe that the Ingersoll Rand T-30’s is a 2-stage so I believe yours is. It makes sense then that on the second stroke there will be greater resistance as the pump is compressing already partially compressed air, even if it is being manually operated by you turning the sheave.

Second, if the T30 starts empty, which essentially is the same thing to removing the belt which eliminates any back pressure on the pistons / motor on start up,  then, please let it run up to cut out, and monitor the unloader valve to be sure that it’s working.

Third, if the unloader checks out, then I’m not sure that what your compressor is experiencing is not a motor issue.

Please visit this page: https://about-air-compressors.com/troubleshooting-your-compressor/ and look in the Capacitor section and Starting Problems section for some information about what the capacitors are and how they affect the starting of the compressor.

If the caps check out, then it’s time to pull the head off the pump and check out the valves, gaskets and pistons / seals.

Let us know what you found out, will you?