2nd stage high pressure alarm is coming and the compressor is tripping. can you pl suggest

since you have not given model number, we will auume it is a 2 stage recip compressor. I would inspect and replace 2nd stage suction valves. have you lost oil and the interccoler is restricted.

Change of Pressure sensor. Or Recalibrating is required.

2 or 3 stage compressors normally run at a constant speed
the stages are from different size pistons
1st stage is a large piston for low pressures that feed to a second smaller piston for higher pressures and for 3 stage to an even smaller piston to get really high pressures
for example 1st stage =100psi
2nd stage =1500psi
3rdstage =3000psi
your manual should explain the set pressure for the compressor if the compressor speeds up , that is a two speed unit

Since I am not there and can't see what is happening this might just be a WAG, but when my air compressor does that, it is either the pressure has been set too high, and when it reaches the maximum rated setting it trips the over pressure switch that trips the reset button.

It has also happened when the pressure regulator whent out and did not sense the pressure that it was supposed to turn off on.

pull the heads and check the intake exhaust valves most likely bad broken valve in the high pressure side

3 stage? It sounds like the first stage has a leaking valve, possibly second stage also - this would explain both the high temperature in stage 1 and the poor pressure from the final stage. Take a look at page 6 of the following link. This is the typical intake and outlet valve diagram for each stage. Valves #2 are intake valves, and valves #6 and 7 are discharge valves. They all perform like check valves, each valve allowing air flow in only one direction. It sounds like your valves are leaking between 1st and 2nd stages. Possibly debris in the valves, or valves damaged. Try taking air intake filter off and check for damage to air filter and debris at intake. Also try removing valve plates and check for debris/damaged valves on first and second stages.

http://www.irservicenet.com/filestorage/SCD-749_.pdf

well,fit a pressure gauge in the 3rd stage so that you can read at which pressure the over pressure valve is working,at the same times you will confirm if the over pressure valve is not faulty

normally you have to change a whole cylinder head kit,

Hi it sounds to me like what actvates the 2nd stage of the compressor is not turning the compressor on when the ambeint temiture reaches the point that it calls for the 2nd stage to start it may be an out door thermostat or a ambient senser and I would request a new Tec to come out and ckeck

Hi. I would suggest having the internal o-rings checked. One of them could be worn, allowing the air to escape. Or put it into your local dive shop for a service.