A residential HVAC system with high or low pressure safety switches would be a surprise. A failed run start capacitor would be the first thing to check. If the capacitor is OK. Check the compressor. Remove the cover where the wires are connected to the compressor. Trace the wires to where they are connected to the power relay and capacitor. Carefully observe and mark where they were removed. These will be the run start and common connections. None of these should read to ground. Do not try to remove the wires from the compressor. I only mention this so as not to damage the fusetite terminal assembly. (there is system pressure behind the terminals) Hopefully it is a defective capacitor. The only other device that comes to mind may be a compressor dead headed against a stuck reversing valve. (thats a reach) Allowing the compressor to continually try to start is not a good thing. There is an internal overload inside the compressor. When it cools down and closes the circuit the compressor will try to start. Last but not least check the supply voltage it should be 220v. Good Luck