# Dead? compressor



## Odysseus

I have an Alltrades Pro 5 HP 27 Gal tank air compressor which was working fine last time I used it, but when I tried to use it recently, I found that all of the air had leaked out of the tank, and it would not start. 

There is power to the wall outlet, but the pump doesn't make a sound, or respond in any way when the off/on switch is flipped back and forth.

I am not mechanically experienced with compressors, so please take into account with any replies. Thanks for any questions and suggestions.


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## Odysseus

Does anyone know of a forum where I might get some help with this?

Thanks


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## tractornut

Is there a circuit breaker on the motor that may have popped?


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## Odysseus

Tractornut, thanks for yours.

With apology, as I do not understand electrics, am I looking for a lever or button that has changed position (i.e., turned off) and where might I find it?

I am attempting to attach a picture of the motor portion.


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## Odysseus

Had a thorough look at the motor/pump, but do not find a reset switch. The pressure switch box is visible in the attached (I hope) photo with the off/on switch visible at top of box.

With the cover off, the off/on switch in the off position and the plug in the wall, the screw in the lower right is hot.

When the off/on switch is moved to the on position, the screw in the lower left of the photo is also hot.

So given that the tank had no pressure and the compressor was plugged in, it appears to me that the air leaked out and it ran, in my absence, trying to build up pressure until something switched off to protect the motor, or the motor overheated and is frozen. Without a reset button, and with my limited skill set, I either need to take it to someone who can diagnose it correctly, or buy a new motor/pump.

The cost of a skilled tech to diagnose it might be higher than a replacement motor/pump, and if it needs the latter, I must then add the replacement cost to the cost of diagnosis.

Any suggestions at this point, and if to replace, and suggestions as to where to find another 5 hp motor/pump to replace the current?

Thanks.


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## tractornut

If you left the switch on it should just run long enough to build pressure then turn off unless it is unable to build pressure ie: the air hose blew out or another large leak developed. The reset switch on my compressor is a red button on the rear of the motor. Yours may be different. I would suggest unplugging it then removing the cover on the motor where the wires enter it then checking for continuity between the plug and the wires at the motor with the switch turned on check all wires if all test good then you need a new motor. 
If one tests bad then test between the plug and the terminals in the pressure switch if those are good check between the connections on the switch wig the switch on. If bad replace the switch if good test between the switch and the motor if bad replace/ repair the wiring if good call a service tech 

Hope this helps


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## Odysseus

Very helpful thanks. Unfortunately my multimeter has gone walkabout, but I have a hot circuit tester (glows red in presence of current). Can I use this for testing "good/bad"?


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## tractornut

That should work but may not allow you to deferentiate between the hot and neutral wires


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## pawon

First,

Make sure that the compressor is not seized. Check if you can run it by hand.

Second, having a multimeter really helps... You can buy one for $2 nowadays.

Check both 'before' and 'after' the pressure switch if you have power. Then, check on the motor connections (if your motor has any), if there is power.

I once was given a small compressor (Atlas Copco), which had a bad thermal protection inside the motor. 

The thermal protection had triggered, but hadn't return to normal after cool down (like it should). So, I just removed the thermal protection completely and connected the wires directly together (with heat-shrink as protection).

Unfortunately, the thermal protection was quite hard to reach... I had to do it 'surgically' trough a small opening...

Here's some pictures I took...


















Since I had to upload the pics anyway, I decided to make it a blog post on my website.. here it is: Small air ompressor repair | Air Compressor Guide 
(sorry, mods, not trying to spam here!)

Let me know what you find out with your compressor, hope we can repair it together here at the forum.


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## EngineMan

Give the pressure switch some WD40 there will be a spring that switchers the power on and off, give a little time, come back and tap the black box. reset button if there is one should be on the motor a red button.


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## Odysseus

Pawon,

You nailed it! Turned out to be the heat protection device which had melted and which, as you warned, was buried pretty deeply in the motor windings. The good news is that a replacement device is pretty cheap (the part anyway).

Thanks to all for their contributions.


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## tractornut

Glad you found the problem and that its a cheap fix


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## shanonmethod

Check electronic circuits of compressor and also check the voltage power supply when you started it.If you compressor make no sound at started then take it into mechanic and change or replace the damage portion of compressor.


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