Sullair Air Compressor Won’t Start – Sullair Compressor Troubleshooting

Published Categorized as Air Compressor Won't Start, Sullair 9 Comments on Sullair Air Compressor Won’t Start – Sullair Compressor Troubleshooting

Hey! This site is reader-supported and we earn commissions if you purchase products from retailers after clicking on a link from our site.

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!

Additional Sullair Air Compressors Pages On

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 comressors


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!

By Aidan Weeks

A passionate Mechanical Engineer with endless enthusiasm for fluid power - building off the back of over 18 years of high quality contribution and discussion stimulated by Bill Wade here at About Air Compressors. With both practical and theoretical experience in pneumatics and hydraulics, I'm putting my knowledge to work - and working my grey-matter through my research, assistance and publishing work here at About Air Compressors. Feel free to reach out any time! P.S. A HUGE shout out to Doug who really offers such great value to all visitors to About Air Compressors - once again, feeling like I'm standing on the shoulders of GIANTS by getting to work alongside such a great community

Notify of
Inline Feedbacks
View all comments

Hello. I have a Sullair 375 with a John Deere. It cranks but it seems that the compressor is loaded all the time. I took the start run valve off and cleaned it. It works as intended. There is oil in the compressor. Engine oil is bang on. Coolant is topped up. I bled the fuel filters, lines and the injection pump. Little bit of smoke coming out of the exhaust. Tomorrow I will check voltage at modules and computer. But I’m starting to lean towards timing or injectors. Let me know what you think. Thank you

Is this a new problem, or a new-to-you-compressor?

I have a Sullair 5500 at my plant. When we go to turn it on, it trips the main breaker. We thought it was a power issue so we hooked up a generator to it and it kicked the generator out too. I have checked the MPV, rotation, etc …… Is there something I’m missing. The thought has crossed my mind of a collapsed separator, but not for sure.

So, it powers up, but when you try to load it it blows the breaker?
Does it make pressure?
BTW, you have a 75+ HP generator?

It doesn’t even load before it trips the breaker, Doug. We even put a generator to and it shut down the generator. And doesn’t even start to build pressure

You say you checked rotation – so the motor starts or tries to when you power on?
Does it have VSD?

Yes, we have checked rotation. We have pulled the coupler and the motor will run without tripping anything. The air end spins freely. I have pulled the check valve at the inlet and it’s not stuck. I have pulled the separator filter, it’s not collapsed. It doesn’t have a VSD. However it does have a spiral valve. My thinking is that spiral valve may causing it to trip everything out. Others seem to think that there’s too much Sullube in the air end and could be flooded. But I don’t see flooding with my mirror. We have megged the motor… Read more »

Uh, spiral valve?

Anyway. Have you checked the fan motor?
Are you getting anything on the controller?

I think it’s time to start disconnecting stuff. You’ve got the fan and compressor motor on one tap – Disconnect – maybe just pull fuses or relay – that. If it still goes then that other board or the transformer is the problem.

Is there any thing to do i try replacing p1 service but still the same