SPECIAL NOTE ABOUT TROUBLESHOOTING-It is up to you to not only read all the information about your problem, but it is also your responsibility to make an informed decision. If you have not properly diagnosed a problem and you just "throw parts" at your problem, don't get upset with anyone except yourself if you don't understand what you are doing or understand the complexity of the problem. You still have the choice or alternative of taking your equipment to a trained repair shop. If you buy parts and it did not fix your problem, you either improperly identified the true problem and purchased the wrong repair item or you have more than one problem.
If you have air leaking from any line or the pressure switch after the motor has shut off, you probably have a leaking TANK CHECK VALVE.
Just because you installed a new pressure switch and it is "also" leaking, does not mean the new pressure switch you installed is bad. You can have two problems. Air leaking from an "unloader" valve on the pressure switch continuously (after the motor shuts off) is an indication of a leaking check valve, not a bad pressure switch. Air leaking from the unloader while the motor is running is an indication of a bad unloader valve.
Special Note about Unloader Valves- Unloader valves do just what the name implies, it is designed to "unload" the pump and air lines after motor shutdown. This feature permits easier starting of the pump motor when it starts up. If air pressure were to remain on the air lines between the pump and the tank, it would be more or "most" difficult for the pump to start pumping trying to overcome the "static" pressure on the pump head. Therefore, designers created the "unloader" to remove air pressure from all lines and the pump head after motor shutdown. If you have continuous air leakage after shutdown, it is doing its job and your check valve is leaking. The check valve is a totally different part, threaded into the tank. DON'T CONFUSE THE TWO VALVES as they serve two totally different purposes.
The check valve is a one way valve designed to permit air flow into the air tank, but not out of the tank. The pump producing the air pressure sends air into the tank through the check valve. Once the air is inside the tank, it should stay there unless some other fitting on the tank is leaking. If you have any air leaks around your pressure switch, the check valve should be checked, cleaned, or replaced.
Caution and safety measures should be considered when opening any lines with air pressure on the tank. If the check valve is leaking, tightening any air line fittings in an attempt to cause a leak to stop is probably not going to stop the check valve from leaking. A leaking fitting is simply a leak and evidence of a leaking check valve, but the most probable cause is the leaking check valve.
You can try to clean the check valve with soapy water. If that does not work your only option is to replace the check valve. Pictures coming soon.
The piston ring or cylinder wall might be worn or damaged.
The valve plate "reed valve" might be broken.
There might be an open valve or air leak down stream of the air tank,
in the air circuit that might be open dumping all the air pressure.
Does the air pressure gauge work properly, do you really have air pressure ?
1. Either the pump is not pumping enough volume
to develop the air pressure
2. Something is leaking out the air
and it can't reach the point of shutoff.
First off, this model uses an "oil less" type of pump. The piston and cylinder wall is dry. This causes a lot of heat build up and can wear out the ring on the piston. See page below for piston and cylinder sleeve. http://www.arkansas-ope.com/COLEMAN_048-0074.html
Inspection areas for the model 10 compressor, ( models ending in 10 ).
Inspection point- Piston and Cylinder You will have to remove the Top valve plate to make this inspection. And maybe the piston and cylinder sleeve. With a light source, inspect for a gap between the piston ring the the sleeve. If the ring is damaged or has "day light" between the piston and cylinder, then there is a compresson leak and this must be corrected. Only thing to do is replace piston and sleeve.
Inspection point- Valves on the Valve Plate. While you have the valve plate off, inspect the "finger" valve reeds. They get hot and break off. Any small piece broken off will prevent air build up.
Inspection point- Check valve at the tank. The check valve is desicned to keep air in the tank. If air is leaking out of the tank through the check valve this will cause a slow or lack of pressure build up. Some times soapy water can clean the check valve otherwise replacement is your only other solution.
The tank check valve could be leaking causing the motor to overload against
backpressure on the pump.
Improper power going to the motor, low voltage condition.
Improper oil in the air pump crankcase
causing the pump to load the motor on startup.
Bad motor, weak and worn out.
Weak circuit breaker.
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