Husky H1506F stopped building pressure past ~15 psi, narrowed down to check or unloader valve

by John
(Wylie, TX, USA)

I've read through the majority of posts, so I'm sorry if I duplicate a question/answer here, but I need your help.

I have a Husky H1506F "pancake" compressor.

During regular use the motor made an odd change in noise, just for a second, sounded like something gave way, but then continued to run normally, except no more pressure built up. I think I've narrowed the problem down to either the check valve or unloader valve. So here is what my observations are:

1) Compressor runs air into the tank (not more than about 15 psi), and it holds for several hours once I turn the compressor off.

2) When the compressor is running there is continuous puffing air that comes out of the unloader line with the unloader valve removed. When the compressor is off there is no air escaping from the unloader line.

3) When the unloader valve is attached to the unloader line, the puffing air continues to escape through the valve release hole while the compreesor is running.

4) How do you tell a defective unloader valve? I have a "condor" style straight unloader valve, and the actuator pin is depressed/not sticking out at rest (holding it in my hand). I've seen pictures of new unloader valves online and they show the pin sticking out, could I have a faulty unloader valve?

5) Although my tank will hold low psi air, it is possible I have a faulty check valve that is allowing higher pressure air to escape, but keeping in a lower psi?


Bill says....

Hey John. Thanks for taking the time to actually read some of the info on the site. Many folks just ask, and don't realize that there are pages here with the answers already posted to their compressor problem questions.

If your unloader valve is dumping air all the time after the compressor stops, then that points to a leaky check valve.

When the compressor is running, is air being pulled into the air compressor via the intake port? You may have to remove the intake filter to check.

If air is being pulled in, pull the line from the pump to the tank (after dumping air). When the compressor is running, can you stop air from flowing out of the port to the tank by putting a piece of cardboard or plastic (not your bare hand) over it?

I'm thinking that you may have a valve or gasket failure based on what you have posted.

An update as a comment here would be appreciated.



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Oct 22, 2011
for the benefit of others...
by: John

After researching I found out that the Husky H1506F (type 1) pump is the same as the pump on the Bostitch CAP60P-OF (OL195 Pump). I was able to find the valve plate assembly from Bostitch Valve Plate Assy. - AB-A640050 part number.

Oct 22, 2011
by: John

Thanks for all of your help! I found the culprit! You were right, the problem was a broken/chipped valve in the valve plate assembly. When I took the manifold off the first time I didn't separate the valve plate assembly (it was stuck to the manifold). So I took it apart again and I can clearly see a chipped exhaust valve. Now the challenge is finding the right part replacement!!!

Thanks again!

Oct 22, 2011
Pump part diagram
by: John


Here is the diagram of the pump itself of a newer revision of my model (it's mostly the same). You were saying something about the high pressure valve, would that be part of the valve plate assembly?

Oct 22, 2011
Cylinder head
by: John

Ok, I think I've located the intake port. It's on the back of the cylinder head. There is no filter. The cylinder, intake port assembly looks like its all one piece. I'm not sure I can open it up to see if it's clogged or anything...

So you think it's a problem with the compression (or lack of) created by the cylinder? I also took apart the manifold and I can see the reed valves and exhaust on the cylinder and cylinder head. It all looks "normal". This unit is only 5 years old and lightly used.

Oct 22, 2011
more troubleshooting...
by: John

Hi Bill,

Thanks for helping me out. The unloader valve does NOT dump air all the time after the compressor is off.

You'll have to help me locate the intake port, I've disassembled almost everything and I can't find what is the intake filter/port. Is it part of the pump? The diagram of my Husky is at this link:

I pulled the line from the pump to the tank, as you suggested, and I am able to stop the air with a piece of cardboard from flowing out.



Your intake port is probably on the end of the pump. There doesn't appear to be a filter. Now that I see the parts diagram, I am suspecting that the intake or high pressure valve is part of, if not all of, your compressor problem. I have not taken one of these apart so I can't tell you further than that. I have a similar pump which I will, in time, disassemble to publish details, just haven't got to it yet.

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Husky doesn't stop running ... it reaches just over 155 psi

by Mark

I have a small 1.5 Hp Husky air compressor about 2 yrs old. It is a 155 max psi and was working great untill recently.

Once it reaches just over 155 psi the release valve opens and pressure drops to about 60 - 70 psi.

This cycle keeps going with no end. I've tried looking for a switch to adjust the pressure but has none. Any ideas on what might be wrong with it. The model is H1503TP

Bill says...

The device that turns the compressor on and off is the pressure switch.

If the compressor is not shutting off at the normal cut out pressure, then the compressor switch is probably failing.



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Aug 14, 2014
Not the switch
by: Bill

Thanks for the feedback.

Here's the thing. If you look at the pressure switches on the smaller DIY type air compressors, you will soon see that for the "house brand" air compressors, there are only a few pressure switch manufacturers. These few companies make the pressure switches for hundreds of thousands of small air compressors sold around the world. The air compressors are low cost, therefore, the pressure switches are too!

Having said that, if the cut out on the pressure switch is set to 155 PSI, and the compressor runs past that pressure to, say, 159 PSI and then shuts off, that wouldn't surprise or bother me, as the variance would be due to the relative accuracy of a low cost device.

If, though, the PRV lets go at 159 PSI and the compressor hasn't stopped running at this point, either the pressure switch has failed, and I would expect, so too has the PR valve.

The PRV is a safety device, the second line of defense should the pressure switch completely fail with the compressor on, and then, the PRV is the only thing that will prevent the compressor tank and air lines on the compressor from over-pressurizing to, perhaps, a catastrophic end.

If your PRV is letting go at 159 PSI for example, and your pressure switch is set to cut out at 155, then I would surmise that the PRV is failing. Usually the margin between cut out and PRV release is measured in 10's of PSI, not a few PSI.

You don't say what the normal cut out of the compressor you have is, nor do you indicate the cut in and cut out settings on the new switch. Are you sure that the settings are correct?

Aug 14, 2014
by: Anonymous

its not the switch ihave the same problem changed the switch does not work

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husky oiless 26 gallon piston freezing

by Steve
(Chandler AZ)

Greetings! i pulled the cover off and the round metal that the piston is connected to is pushing out causing the piston to grind against it, up to 25 psi, its not bad, but after that it comes out hard. my friend noticed the problem and we C-clamped it back in, but it lasted 10 minutes.
Steve, I'm happy to post this for you, though it will be difficult for folks to help without knowing the model number of your Husky.

Also, some photos would be a big help.

Why not start another thread in the Husky section, identify the model, and send in some photos (up to four) so that folks can see what you are referring to?



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Husky 33 gal. compressor not powering on

by Scott
(Columbus, Ohio)

Hello, I have a Husky 33 gal. compressor, I bought it as refurbished and the label containing model etc. is not intact.

When it's plugged into the wall outlet and the tank is drained to empty it won't automatically turn on to refill. I've tested the GFCI and the breaker, neither are tripped. The outlet is good, I've plugged in other appliances and they work normally. Not sure what else to check.
When the tank is empty the pressure switch should have tripped to the passing setting, which means that power should be flowing through the pressure switch to the motor circuit, Scott.

Is it? You'll need a multimeter to check.

Post a comment here with your findings if you would.


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