Has Unloader Valve Issues


Your compressor has unloader valve issues? The unloader valve provides a critical function in the restarting of an air compressor.

This is a forum page providing information and a place to post a questions when your compressor has unloader valve issues.

Not entirely sure what the unloader is and does? Here is operating information on Unloader Valves.

Essentially, when the unloader valve does not dump the air over the piston when the compressor stops, the compressor sometimes cannot restart.

If you think you've got a problem with your compressor unloader valve, why not scan the questions and answers at the bottom of this page. In the event that your problem is not noted there, do please add it using the form just below.

And, if you can offer advice on any of the questions, it sure would be appreciated. Then we all benefit from your compressor experience.

Thanks,

Bill

Problems with your compressor unloader valve?

Please if you have unloader valve problems, and the answer isn't already noted below, post the details.

Compressor has unloader valve problems?

Questions and answers are posted below.

kobalt 2hp boggs on restart. Trips breaker 
I bought a small kobalt 2hp - 60 gal unit slightly used for garage. The belt was loose and slipped on restarts. I thought it was bad adj but now am certain …

LGM 125 unloader valve on 10HP DeVilbiss compressor. 
I re-installed the original LGM125 unloader on my 10 HP Devilries compressor. It operated properly after the compressor limit switch turned the compressor …

unloader line blows off 
I inherited a Kobalt 60 gal compressor (no. 221565)from the previous owner of my house and it ran fine (once I cleared the mud wasp nests out of the motor)until …

Can I replace the copper unloader tube? 
Hi Bil: Can I replace the copper unloader tube with a flexible metal braided line? Here's the situation. I have two oilless compressors. …

New unloader valve does not have compression fitting 
I just replaced the following on my Campbell Hausfeld compressor: CV209301AJ: regulator assembly CV303100AJ: Pressure switch assembly I did not …

Unloader valve starts bleeding off air through valve when top pressure is reached 
I just installed a new pressure air switch and am still have trouble with the unloader valve. When the compressor reaches max. pressure the unloader valve …

Compressor cannot unload even after the blowdown point 
Compressor cannot unload even after the blowdown point. On getting to the set point of blowing down, the compressor will continue to build up pressure. …

loss of pressure when compressor stops 
when the compressor stops at pressure set point the end point uses loose pressure , the pressure is not maintained when the compressor stops

New check valve, new bleeder valve, still not working 
I built a silent air compressor using a refrigerator compressor mounted on a craftsman 3 gal tank that was complete with the pressure gauges, regulator …

2 way pressure relief valve does not need an unloader 
If a compressor switch says it has 2 way pressure relief valve, does it mean that it does not need an unloader. A compressor switch I was looking at …

2hp compressor tripping breaker on 2kva generator 
Hi Bill Compressor runs ok on mains power (240) and also fills from empty on genset. Cuts out OK and dumps at 120 psi However it won't cut back in at the …

Dresser series 400 unloader valve plumbing ??? 
I just bought a used dresser series 400 air compressor and Im not sure how to hook up the unloader valve plumbing... right now it has the two unloader …

unloader problems compressor will not cycle 
Compressor will not cycle - hums tries to turn over but cannot - blows a new 20 amp circuit breaker - I've had it to the compressor repair guys twice - …

When running air keeps pouring out of air compressor unloader valve ... 
I wanted to make a "silent air" compressor out of my HF oil compressor. I took off the original (new) motor and replaced it with a motor/compressor from …

Compressor unloader valve bleeds air all the time ... 
I have a Campbell Hausfeld 13 gallon air compressor, model #WL604004AJ. The unloader valve (part #CW00800AV) dumps air 90% of the time. I installed …

Compressor will only start with little or no pressure in tank ... 
Bill; The compressor is a Norther Industial Tool 2 HP 8 Gallon. The compressor will only start with no or very little pressure in the system and …

Sears compressor unloader valve not working... 
Hi! I have a problem with a compressor pressure switch which has a leaking unloader valve. The valve lets out air immediately when the compressor is …

Compressor unloader tube leaking ... 
Hey Bill, I've an old compressor which has been kept going with a quick service- it's a Gianesi Edilio Zavaterello- I have no idea what it's background …

Compressor struggling to restart... 
Hi There, I have a cheap 45 litre tank compressor. When i use the compresser at the start of the day , it will not pump and buzzes for a few seconds …

What the compressor unloader valve does... 
I am having no luck figuring this out. Hope you can help. I bought a new v-twin compressor with head unloaders. I know what unloaders do but I am …

Buffalo Pneumatic compressor unloader valve no longer works - replacement? 
My 5HP compressor marketed as a Buffalo Pneumatic and purchased about ten years ago from Home Depot has a defective unloader valve. I've tried rebuilding …

My unloader valve is too noisy .. 
Hi Bill I have a silent compressor with the unloader built into the pressure switch. Is there any way to reduce/muffle the noise when the unloader operates? …

Air compressor will not autofill correctly ... 
At the start of the day with pressure at 0 psi, the compressor will start up fine and fill the tank to 150 psi. As air is used and drawn down, the compressor …

Compressor shuts off and valve leaks ... 
I dont see any check valve it has the same set up as the unit you used to show the release valve __________________ G'day Steve. If air is bleeding …

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Unloading valve doesn't close after changing air compressor motor ... 
Hi Bill, I bought a used 2hp air compressor with 24 liter tank and replaced it's motor with an air conditioner 1.25hp compressor. Now I'm having …

Compressed air keeps running - unloader not working 
dear sir i had solenoid valve issue in my electric screw compressor 30 KW, the unloading operation is not proper. when i clean solenoid valve the …

Compressor trips breaker but not when empty ... 
Hi,my compressor tries to start but struggles for around 10 seconds then it blows the trip. If the tank is empty it will start with no problem and run …

Compressor unloader valve failing... 
On start-up, the compressor will fill regularly, but when it needs to refill, it struggles and sounds like it is cutting out, until the internal breaker …

Compressor won't kick on when pressure drops. 
My compressor will only start if there is zero pressure in the tank. I thought the problem was too much pressure on the head & sought to solve it by replacing …

Unloader valve malfunctioning... 
where can I purchase the unloader valve you show in your example. I need that exact one and the so called dealer says they can not get it. ____________________ …

My compressor unloader valve problems... 
I have a 60 gal 5 hp single phase compressor (energair) i bought at an auction. It has a 1/2" copper line off the compressor head to a tee in the tank. …

Do I need an unloader valve on my switch... 
my compressor motor will start up fine with no air in tank, however, when the tank is being used and the switch trips the motor to come on the motor wont …

Compressor unloader valve is leaking continuously ... 
Unloader Valve wood not stop trowing air out _______________________ Bill says... Joseph, I doubt if it's your unloader valve that is causing …

Air compressor not unloading... 
I have a Husky (Campbell Hausfeld) 80 gallon 2 stage compressor and it does not unload when it reaches capacity and when I drain air down it kicks reset …

Air is leaking at the pressure switch end of compressor tube ... 
DEVILBISS Upright 5.5 hp. Model No. FB5520VP When shutting off at cut-out pressure, or when manually turned off, air continues to escape at the right …

Is unloader tripping breaker... 
The Swan tech came out today, and lengthened the discharge line a fare amount by going around the whole compressor unit, giving ample time for the motor …

Adjusting the compressor unloader valve... 
I have built compressors for several years but i am having a problem in the electric motor restarting after the pressure switch has reached set pressure …

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