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by Jeff
(Kansas City, MO, USA)

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.


Sullair waiting for blowdown
by: Doug in s.d.ca.

Any particular model you’re dealing with?


Model and repair outcome
by: Jeff

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


by: Doug in s.d.ca.

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

Have you checked the check valve, too?

Help on 7507

by: Dustin

Jeff did you figure out why is was saying waiting for blow down I am having the same issue


It was a bad P1
by: Jeff

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


Bad P1
by: Bill

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.