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There have been many folks that wish to inquire about why their Sullair air compressor not turning on and other questions along those same lines. This article will present some of the reasons this may be happening and provide Sullair air compressor troubleshooting suggestions to resolve those issues, along with existing reader problems.

Table of Contents

Reasons Why Your Sullair Air Compressor Won’t Start

The main reasons as to why your Sullair air compressor hums but won’t start are likely to be due to any of the following reasons summarized in the table below:

Power issueAvoid using power bars and power strips.
Faulty pressure switchUnplug the Sullair compressor from the electrical outlet before opening the drain valve releasing the air from the tank down to zero and then closing the drain. 
Fuse or breaker blowsCircuit breakers will trip off when a power surge blows their fuses. If the fuses are faulty, you will need fuse replacements.
Faulty unloader valveCheck unloader valve, if faulty pressure switch may not work.
Faulty thermal overload switchCheck the thermal overload switch to ensure it is working correctly.
Insufficient oilCheck the oil level, and inspect the pump area for any potential leaks.
Reasons Why Your Sullair Air Compressor Won’t Start

Please visit our Air Compressor Won’t Start – Ways to Fix Air Compressor Won’t Turn On Problems guide for more detailed Sullair air compressor troubleshooting & fixes!

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Reader Questions and Responses

Sullair Air Compressor Won t Turn On – Sullair Air Compressor Troubleshooting


In automatic and manual, the compressor will not start, saying it is waiting for blowdown.

The manual says the sump pressure is too high, the indication is around 15 pounds. It seems like the blowdown is working, but we might have a check valve leaking back, and potentially a pressure detection issue.

With the discharge valve close, we can get pressure down to 6 pounds.

I wonder if we should take the check valve out and try to clean it up? Any other advice would be great.


Any particular model you’re dealing with?


It is a Sullair Model 7507, we had it serviced and they replaced the pressure transducer P1 and rebuilt the MPV.

Sullair model 7507 air comressors
Sullair model 7507 air compressors


So, did that rebuild and transducer fix it, or was that before you first wrote?

Have you checked the check valve, too?


Jeff did you figure out why it was saying waiting for blowdown I am having the same issue. Dustin


The pressure transducer P1 was bad, and we had some leak back from the air system. Jeff


Hey Jeff, thanks for taking the time to come back and reply to Dustin.

It’s great when my site works the way it’s supposed to… compressor folks helping other compressor users.

If you have any questions regarding the Sullair air compressor won’t turn on, please leave a comment below, with a photo if applicable, so that someone can help you!