Kobalt air compressor problem plastic tube gets a hole

Clearly there is an air leak and ignoring the (obvious) possibility of a leaky tank or drain valve or exposed pipework it leaves two possibilities - either the electrical pressure switch diaphragm is failing or the compressor nonreturn valve is failing.

I suggest you switch on the compressor and when air receiver has a partial charge disconnect the power and attempt to locate the leak.
Use a couple of feet of hose as a listening aid for large leaks and a little detergent solution to pinpoint small leaks...

Abandon the display and install a generic pressure switch at a convenient port. Example. Remove the safety valve and install a tee fitting. Re-install the safety on one port of the tee and a pressure switch on the second port. Generic pressure switch on Ebay is about $15 dollars. The pressure switch usually has other ports to install gauge and quick fittings. Will not look pretty but will work nicely. Good luck

The head pressure is released thru the needle unloader valve at the pressure switch. Notice a 1/4 inch plastic tube (or metal) running from the intank check valve to the pressure switch. After pressure switch reaches set pressure a small tang moves up and presses on the needle valve releasing the pressure. Only a small amount of air will be released. If however air continues to escape from the needle valve, then the check valve is bad.

You may be able to replace the plastic line with copper tubing.

Buy new pressure relief valve, I have in stock.

no, do not block with a solid plug. This allows air to bleed off the compressor so it will restart when pressure switch makes. If air continually bleeds out of this hole i would check the tank check valve . It is bad or has trash or something keeping it from closing. If check valve is bad it will allow air from the tank to bleed down until compressor starts or no air left in tank if shut down

This sounds like the compression release valve is leaking. This valve bleeds the cylinder pressure to allow the motor to start without having the load on it. On this size compressor the valve is often built into the pressure switch. It is a little "pintle" type valve and you will hear hissing while unit is running but the opressure will not build up very much. When the pressure switch calls for the unit to run, the little valve closes with the switch. COntamination or other stiction keeping the valve form closing will cause the problem. You will find this near a tube that goes to the pressure switch. The switch itself hooks into the tank, but this little tube will connect to the cylinder head or the main tube from the compressor. Yours may look similar to ones at this site:
http://www.generalairproducts.com/Fire-Protection-Products/accessories-pressure-switch-a-switches-check-drain-a-pressure-relief-valves.html
The valve is also commonly called the "unloader" valve.

The 1/4" line is very necessary and there are no adjustments on it. When the tank reaches full the pressure switch turns off the power and opens the valve to the 1/4" line to bleed off pressure from the air pump and feed tube so the motor can turn over the next time the tank drops to the kick in pressure. Every time the pressure switch turns the motor off a small amount of air should be heard coming out of the bottom of the switch for three to five seconds and then it should stop completely. If air continues to leak out of the switch by the 1/4" line, you have a bad tank check valve. The tank check valve is the brass fitting at the other end of the 1/4" line where the feed tube from the air pump goes into the tank. It keeps air in the tank after the pressure switch turns off the motor. Easy to replace, find the one you need for your model compressor.

Most pressure switches use a diaphragm to activate the contacts that may leak, however, air leaking from the unloader after compressor reaches cut-out is result of in-tank check valve. Easy to check. Turn off power to unit and remove 1/4" tubing at the check valve (follow 1/4 tubing from pressure switch to check valve). If leaking remove from tank and clean debris under seat or replace with generic from www.grainger.com Good luck

The air is probably coming through the unloader on the pressure switch. This is designed to vent the pressure between the compressor pump and the tank so that the compressor starts easier. This venting should only take a few seconds (5 to 10). If it bleeds air continuously, until the compressor restarts, then the tank check valve is bad. This is usually a fitting that extends into the tank. The small tube to the unloader usually goes directly from the pressure control switch to the tank check. Depressurize the tank, remove the check valve, and try to clean it. If that doesn't work, replace it.