How to replace an unloader solenoid - air compressor bleeding air, not building pressure
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- เผยแพร่เมื่อ 15 ก.ย. 2024
- This video shows how to troubleshoot and replace a bad unloader solenoid (similar to an unloader valve) on a GMC/California Air Tools compressor.
The symptom of a bad unloader is the sound of air rushing out while the compressor is pumping, and pressure is not building in the tank. This is because the unloader solenoid that should be closed during pumping is burned out, and the unloader valve keeps bleeding pressure that should be going into the tank.
It's easy to obtain the solenoid from the manufacturer, but not so easy to replace the whole unit due to space constraints, so I show a little trick of only replacing the solenoid winding and leaving the rest of the valve in place.
Note: it's unusual for the unloader to be a solenoid. The more normal setup is a mechanical unloader valve. See my related video for an explanation of its operation, along with an explanation of each of the compressor's parts and their function.
Nice and informative thanks for the help now I can repair my compressor.....😊😊😊😊
AWESOME! This is the exact piece of info I needed! My compressor was vandalized and I didn't know where to connect the power for the unloader.
Great video. Mine is humming like it’s about to blow up or something after the tanks are full. So I turn it off then turn it on again then it pumps a little more air for about 5 seconds then back to the humming noise 😬. My compressor is only new. Spewing it’s got problems so soon. Looking at yours it looks so new to. Although this video is 7 years old now lol 😂
Good video, thanks
My compressor is building pressure but the problem is, its not releasing it with pressure. Like if the hose was kinkes but its not. What could be the problem?
I assume what you're saying is that you wait for the compressor to build to full pressure, the motor stops, your tank gauge and outlet gauge both show full pressure, and you try to use the air after that point and it's coming out at low pressure.
Something must be blocked. There's not much in the way between the tank and the outlet.
Play with the pressure regulator, make sure it's all the way open. Does your outlet pressure gauge show full pressure? If not, your regulator is adjusted wrong or broken. It could also be broken in a way that allows pressure to build slowly but restricts flow.
I assume your tank pressure gauge shows full pressure and can be trusted. Air should be coming out under pressure when you open the drain valve or the pressure popoff valve.
To check flow at the outlet and rule out the hose, pop the hose off the compressor side (careful) if you have a quick disconnect fitting. If you don't have a quick disconnect before the hose, install one, so you can do this test. Or unscrew the hose fitting under pressure, which is even more dangerous. If you have a known good hose, replacing the hose would be your safest bet to rule out the hose.
If the blockage is between the tank and the outlet to the hose, trace the path of the air back to the tank, and rule out one component at a time (regulator, fittings, plumbing, tank outlet). Watch my other video on how an air compressor works, it might give you more hints. th-cam.com/video/GbGBK6MIyIs/w-d-xo.html
Try to find the plumbing schematics of your compressor for more hints.
Good luck and let us know what you find.
I believe I am due for a valve replacement on the same exact model. Just curious, what is your typical leak rate on this model, or how many hours between two compressions when not using air? Thanks.
Nico The issue that happens when the solenoid dies is that the compressor doesn't build pressure at all. All the air from the pump goes out the valve. It sounds like your check valve on the tank is bad. You can take it out and see if the rubber piece is clean and the spring is good. I don't have an issue with that valve. Compressor takes a few hours to turn on if left on.
Thanks for your reply man. As it turned out, the problem came from the vent valve at the bottom of the tank. It was installed incorrectly at the factory and part of the thread of the taped hole is dead. Added a bunch of Teflon tape and it looks like it is holding fine for now. The valve was misaligned by maybe 15 degree. Really poor job on their part.
Can you give more detail on the valve? Is it a 2way or 3way valve? How many ports are on the valve? Part number? Any more info would be appreciated. I have another project that this exact valve would be perfect.
Hmmm I'm not an expert on valves and don't have one in front of me, but I'm pretty sure it's a 2-way normally open valve. Two ports - the pressure input side threaded and the exhaust side not (well it's threaded for the nut that holds it together). Very simple. When there's no power applied it lets air through, and when power is applied it closes. You can see more of the valve disassembled at minute 19 in this video: th-cam.com/video/GbGBK6MIyIs/w-d-xo.html
steelddd Thank you. That's what I gathered from what I saw and read. Unfortunately I can't find one online in this style.
TheSandman614 I couldn't find one either, but I did get a replacement from california air tools under warranty. You could try to contact them and see if they'll send you one. They call it "electromagnetism" :D in the manual www.gmcgenerators.com/wp-content/uploads/California-Air-Tools-Air-Compressor-Manual-7-21-11_Layout-1.pdf
Same like my problem 😭