# Air compressor bogs down



## Tin Man (Jun 8, 2021)

I have a 60 Gallon Husky compressor.. when it starts it runs bogged down.. I have changed both capacitor and the relief valve and same issue.. if I drain the tank it will start and run normal till filled.. but once it gets down to the kick in pressure I have the same bog problem.. if I disconnect the fill pipe from the top of the compressor there is no pressure there and it starts and runs at full speed.. but if I try to reconnect it while it’s running it bogs down again.. so don’t know where to go from there..


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## motormonkey (Jul 10, 2016)

When you drain the tank and it starts and runs normally until it is filled, you should hear a hissing noise for a couple of seconds when it shuts off. That is the unloader operating. It releases the air pressure on the output of the compressor when it shuts off. That's so that the compressor doesn't have to start against a full head of pressure the next time it kicks on. You could expect the "bogging down" you described if the unloader isn't working properly.


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## iowagold (Jan 22, 2020)

i agree replace the unloader and the check valve from the pump to the tank.


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## Tin Man (Jun 8, 2021)

iowagold said:


> i agree replace the unloader and the check valve from the pump to the tank.


The unloader valve does hiss when it shuts down.. plus I take off the upper line by the head of the compressor and there is not pressure there.. compressor fires up fine and runs full speed.. but try to,reattach the line and it bogs down.. and I have already changed the one way pressure valve..


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## Tin Man (Jun 8, 2021)

motormonkey said:


> When you drain the tank and it starts and runs normally until it is filled, you should hear a hissing noise for a couple of seconds when it shuts off. That is the unloader operating. It releases the air pressure on the output of the compressor when it shuts off. That's so that the compressor doesn't have to start against a full head of pressure the next time it kicks on. You could expect the "bogging down" you described if the unloader isn't working properly.


Is there such a thing as a start switch in the motor that could be causing the problem?


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## iowagold (Jan 22, 2020)

check the switch with a meter.
and the windings for issues.

some thing is not right.
maybe even a 1/2 blown fuse or bad breaker or bad connection...
things change when under a start load.

also slip a gauge in there and see what is up...
almost like the spin up is not happening ...
maybe the wrong unloader? 
something is dead heading...
or weak on power

do a current meter test on the ac line
what is the voltage and the current when it fails to start up?

how many horse power is this?


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## stevon (Mar 5, 2019)

Tin Man,

Yeah a clamp on ammeter on a leg of the power hookup can tell you a lot. This sounds like a typical bad check valve issue but could be windings or start clutch/switch. Ammeter readings will give you more to diagnose with.

Stephen




iowagold said:


> check the switch with a meter.
> and the windings for issues.
> 
> some thing is not right.
> ...


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