My air compressor just stopped working completely,has power to it and can turn the fan so its not seized but was gonna start by checking the reset relay and what appears to be a capaciter. just looking for a little help,thanks

replace the motor the bearing has seized up.

It sounds to me that your belt or tensioner is worn, if the noise goes away when the ac is off then it is just the belt slipping, it takes a lot of power to run the compressor and if the belt is worn it most likely slipping on the pully when you engage the clutch.

This may have come too late to do any good but I'll post it anyway.

Let's start with the simple.

Verify the lights turn on when you open the door. If not and you know the lights are good, check your circuit (breaker/fuse) panel for tripped or blown fuses. Replace or reset as needed.

If lights work, temporarily turn your temperature knobs as high as they will go and listen for the compressor to turn on. If it doesn't you may have a bad thermostat, or the fridge is in defrost mode which turns the compressor off and the heater on so that it can defrost the coils. To cycle the defrost timer, look for a hole in the thermostat plastic housing cover and with a fairly wide screwdriver blade turn the one way shaft a little bit to a 1/4 turn and see if the compressor and fan turns on now. The timer shaft is sloped on both sides and turns only one way, so if it doesn't engage with the screwdriver tip, turn it the other way and you will feel some resistance when you turn it the right way. If the compressor does turn on, your defrost timer (the part you turned) is likely bad.

If the compressor turned on when you set the thermostat to high, check the ducts at the back of the fridge for cold air blowing from them. If the air isn't blowing, your coil (evaporator coil) fan may be bad (seized up). The fan only runs when the compressor is running. Excessive frost build-up on the coils can reduce or stop cold air from being dispersed in the fridge. If the defrost timer fails to rotate to the defrost cycle, humidity from opening the doors of the fridge will eventually clog the coils with frost and the cold air will be stopped from entering the fridge causing the compressor to run continuously and the interior to be warm.

If your issue turns out to be a compressor or refrigerant issue a licensed professional will have to take it from there.

It sounds like a lot but it's easier than it sounds!

Good luck!

I need the diaphram in the On/Off pressure switch on a Black Bull- 4 Gal., 2 HP, 5.0 cfm @ 90 PSI 120 v /13.8 amp . Batch # 0911. These are the only # I can find

The rattling when it kicked in was either compressor or condenser fan. Check the fan isn't seized and compressor runs.

If after reset the A/C cools then the fault seems related to the thermostat or the cut off pressure switch or load cut off.
However is there is no cooling at all the compressor and the gas pressure- check for leak if gas is absent.- must be checked .
If compressor is suspect you must check the estimate and decide whether it seems better to scrap and buy a new one.

It sounds like your inverter is at fault. You will need an inverter tester ( most good service techs will have one ) to prove that the output to the compressor is correct. If the inverter is okay then it will be the compressor at fault with a location error or it is simply seized. A common fault that caused this was the eev remained closed (coil failure ) and caused the compressor to over heat.

The cooling fan for the condenser is probably running, getting hot and seizing up. Check to see if the fan is free spinning after it stops. Take a probe and try to spin it manually. If it turns freely, then it could be going bad with it's electrical windings, the internal coils that create the magnetic field that spins the rotor of the fan motor. I suspect it is seizing up, however, once a fan seizes up, it usually stays that way and won't spin even after it cools down. It could be a capacitor that is going bad and not starting the fan after it gets hot. A capacitor is a small round shaped can type with usually 2 wires hooked in series with the motor it is trying to start. That is what it does, help start the device (compressor or fan motor). Good luck.Ken from Henderson NV.

Check that the fanmotor can spin freely. If not, can be caused by seized bearing on left side of fanblade, or foreign object, insect nest stuck in fanblade. If however it spins freely, check that fanmotor is being supplied with voltage (you sound technically capable of operating a volt meter). If power is supplied, fanmotor is faulty and needs replacing. If no voltage, problem lies with the pc board. If you know someone who is capable let them check the relays on the board. Also you can check that all plug on connectors are making good connection.

The fan motor must have been stopping. If the fan stops, for sure the fins will freeze because there is no air flowing. common Fan motor problems defective bearing or bushing and starting condenser. If the bearing is defective, it will heat up and seize. Have the fan motor checked. The fact that the fins are freezing, means that there is enough freon and the compressor is working.